[alsa-devel] [Patch v6 1/7] slimbus: Device management on SLIMbus
Sanyog Kale
sanyog.r.kale at intel.com
Thu Oct 12 13:01:46 CEST 2017
On Fri, Oct 06, 2017 at 05:51:30PM +0200, srinivas.kandagatla at linaro.org wrote:
> From: Sagar Dharia <sdharia at codeaurora.org>
>
> SLIMbus (Serial Low Power Interchip Media Bus) is a specification
> developed by MIPI (Mobile Industry Processor Interface) alliance.
> SLIMbus is a 2-wire implementation, which is used to communicate with
> peripheral components like audio-codec.
> SLIMbus uses Time-Division-Multiplexing to accommodate multiple data
> channels, and control channel. Control channel has messages to do
> device-enumeration, messages to send/receive control-data to/from
> slimbus devices, messages for port/channel management, and messages to
> do bandwidth allocation.
> The framework supports multiple instances of the bus (1 controller per
> bus), and multiple slave devices per controller.
>
> This patch does device enumeration, logical address assignment,
> informing device when the device reports present/absent etc.
> Reporting present may need the driver to do the needful (e.g. turning
> on voltage regulators powering the device). Additionally device is
> probed when it reports present if that device doesn't need any such
> steps mentioned above.
>
> Signed-off-by: Sagar Dharia <sdharia at codeaurora.org>
> Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla at linaro.org>
> ---
> Documentation/devicetree/bindings/slimbus/bus.txt | 57 ++
> Documentation/slimbus/summary | 109 ++++
> drivers/Kconfig | 2 +
> drivers/Makefile | 1 +
> drivers/slimbus/Kconfig | 11 +
> drivers/slimbus/Makefile | 5 +
> drivers/slimbus/slim-core.c | 695 ++++++++++++++++++++++
> include/linux/mod_devicetable.h | 13 +
> include/linux/slimbus.h | 299 ++++++++++
> 9 files changed, 1192 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/slimbus/bus.txt
> create mode 100644 Documentation/slimbus/summary
> create mode 100644 drivers/slimbus/Kconfig
> create mode 100644 drivers/slimbus/Makefile
> create mode 100644 drivers/slimbus/slim-core.c
> create mode 100644 include/linux/slimbus.h
>
> diff --git a/Documentation/devicetree/bindings/slimbus/bus.txt b/Documentation/devicetree/bindings/slimbus/bus.txt
> new file mode 100644
> index 0000000..cb658bb
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/slimbus/bus.txt
> @@ -0,0 +1,57 @@
> +SLIM(Serial Low Power Interchip Media Bus) bus
> +
> +SLIMbus is a 2-wire bus, and is used to communicate with peripheral
> +components like audio-codec.
> +
> +Controller is a normal device using binding for whatever bus it is
> +on (e.g. platform bus).
> +Required property for SLIMbus controller node:
> +- compatible - name of SLIMbus controller following generic names
> + recommended practice.
> +- #address-cells - should be 2
> +- #size-cells - should be 0
> +
> +No other properties are required in the SLIMbus controller bus node.
> +
> +Child nodes:
> +Every SLIMbus controller node can contain zero or more child nodes
> +representing slave devices on the bus. Every SLIMbus slave device is
> +uniquely determined by the enumeration address containing 4 fields:
> +Manufacturer ID, Product code, Device index, and Instance value for
> +the device.
> +If child node is not present and it is instantiated after device
> +discovery (slave device reporting itself present).
> +
> +In some cases it may be necessary to describe non-probeable device
> +details such as non-standard ways of powering up a device. In
> +such cases, child nodes for those devices will be present as
> +slaves of the slimbus-controller, as detailed below.
> +
> +Required property for SLIMbus child node if it is present:
> +- reg - Is Duplex (Device index, Instance ID) from Enumeration
> + Address.
> + Device Index Uniquely identifies multiple Devices within
> + a single Component.
> + Instance ID Is for the cases where multiple Devices of the
> + same type or Class are attached to the bus.
> +
> +- compatible -"slimMID,PID". The textual representation of Manufacturer ID,
> + Product Code, shall be in lower case hexadecimal with leading
> + zeroes suppressed
> +
> +SLIMbus example for Qualcomm's slimbus manager component:
> +
> + slim at 28080000 {
> + compatible = "qcom,slim-msm";
> + reg = <0x28080000 0x2000>,
> + interrupts = <0 33 0>;
> + clocks = <&lcc SLIMBUS_SRC>, <&lcc AUDIO_SLIMBUS_CLK>;
> + clock-names = "iface_clk", "core_clk";
> + #address-cells = <2>;
> + #size-cells = <0>;
> +
> + codec: wcd9310 at 1{
> + compatible = "slim217,60"";
> + reg = <1 0>;
> + };
> + };
> diff --git a/Documentation/slimbus/summary b/Documentation/slimbus/summary
> new file mode 100644
> index 0000000..e7f90bb
> --- /dev/null
> +++ b/Documentation/slimbus/summary
> @@ -0,0 +1,109 @@
> +Overview of Linux kernel SLIMbus support
> +========================================
> +
> +What is SLIMbus?
> +----------------
> +SLIMbus (Serial Low Power Interchip Media Bus) is a specification developed by
> +MIPI (Mobile Industry Processor Interface) alliance. The bus uses master/slave
> +configuration, and is a 2-wire multi-drop implementation (clock, and data).
> +
> +Currently, SLIMbus is used to interface between application processors of SoCs
> +(System-on-Chip) and peripheral components (typically codec).SLIMbus uses
> +Time-Division-Multiplexing to accommodate multiple data channels, and
> +a control channel.
> +
> +The control channel is used for various control functions such as bus
> +management, configuration and status updates.These messages can be unicast (e.g.
> +reading/writing device specific values), or multicast (e.g. data channel
> +reconfiguration sequence is a broadcast message announced to all devices)
> +
> +A data channel is used for data-transfer between 2 Slimbus devices. Data
> +channel uses dedicated ports on the device.
> +
> +Hardware description:
> +---------------------
> +Slimbus specification has different types of device classifications based on
> +their capabilities.
> +A manager device is responsible for enumeration, configuration, and dynamic
> +channel allocation. Every bus has 1 active manager.
> +
> +A generic device is a device providing application functionality (e.g. codec).
> +
> +Framer device is responsible for clocking the bus, and transmitting frame-sync
> +and framing information on the bus.
> +
> +Each SLIMbus component has an interface device for monitoring physical layer.
> +
> +Typically each SoC contains SLIMbus component having 1 manager, 1 framer device,
> +1 generic device (for data channel support), and 1 interface device.
> +External peripheral SLIMbus component usually has 1 generic device (for
> +functionality/data channel support), and an associated interface device.
> +The generic device's registers are mapped as 'value elements' so that they can
> +be written/read using Slimbus control channel exchanging control/status type of
> +information.
> +In case there are multiple framer devices on the same bus, manager device is
> +responsible to select the active-framer for clocking the bus.
> +
> +Per specification, Slimbus uses "clock gears" to do power management based on
> +current frequency and bandwidth requirements. There are 10 clock gears and each
> +gear changes the Slimbus frequency to be twice its previous gear.
Does the spec mandate 10 clock gears or its controller property?
> +
> +Each device has a 6-byte enumeration-address and the manager assigns every
> +device with a 1-byte logical address after the devices report presence on the
> +bus.
> +
> +Software description:
> +---------------------
> +There are 2 types of SLIMbus drivers:
> +
> +slim_controller represents a 'controller' for SLIMbus. This driver should
> +implement duties needed by the SoC (manager device, associated
> +interface device for monitoring the layers and reporting errors, default
> +framer device).
> +
> +slim_device represents the 'generic device/component' for SLIMbus, and a
> +slim_driver should implement driver for that slim_device.
> +
> +Device notifications to the driver:
> +-----------------------------------
> +Since SLIMbus devices have mechanisms for reporting their presence, the
> +framework allows drivers to bind when corresponding devices report their
> +presence on the bus.
> +However, it is possible that the driver needs to be probed
> +first so that it can enable corresponding SLIMbus devie (e.g. power it up and/or
> +take it out of reset). To support that behavior, the framework allows drivers
> +to probe first as well (e.g. using standard DeviceTree compatbility field).
> +This creates the necessity for the driver to know when the device is functional
> +(i.e. reported present). device_up callback is used for that reason when the
> +device reports present and is assigned a logical address by the controller.
> +
> +Similarly, SLIMbus devices 'report absent' when they go down. A 'device_down'
> +callback notifies the driver when the device reports absent and its logical
> +address assignment is invalidated by the controller.
Is the same logical address assign when it reports present again?
> +
> +Another notification "boot_device" is used to notify the slim_driver when
> +controller resets the bus. This notification allows the driver to take necessary
> +steps to boot the device so that it's functional after the bus has been reset.
> +
> +Clock-pause:
> +------------
> +SLIMbus mandates that a reconfiguration sequence (known as clock-pause) be
> +broadcast to all active devices on the bus before the bus can enter low-power
> +mode. Controller uses this sequence when it decides to enter low-power mode so
> +that corresponding clocks and/or power-rails can be turned off to save power.
> +Clock-pause is exited by waking up framer device (if controller driver initiates
> +exiting low power mode), or by toggling the data line (if a slave device wants
> +to initiate it).
> +
> +Messaging APIs:
> +---------------
> +The framework supports APIs to exchange control-information with a SLIMbus
> +device. APIs can be synchronous or asynchronous.
> +From controller's perspective, multiple buffers can be queued to/from
> +hardware for sending/receiving data using slim_ctrl_buf circular buffer.
> +The header file <linux/slimbus.h> has more documentation about messaging APIs.
> +
> +-----------------------------------------------------------------
> +<Sections will be added to this document when port/channel bandwidth management
> +support, multi-xfer APIs are added to the framework>
> +------------------------------------------------------------------
> diff --git a/drivers/Kconfig b/drivers/Kconfig
> index 505c676..8010c67 100644
> --- a/drivers/Kconfig
> +++ b/drivers/Kconfig
> @@ -208,4 +208,6 @@ source "drivers/tee/Kconfig"
>
> source "drivers/mux/Kconfig"
>
> +source "drivers/slimbus/Kconfig"
> +
> endmenu
> diff --git a/drivers/Makefile b/drivers/Makefile
> index d90fdc4..0449c7c 100644
> --- a/drivers/Makefile
> +++ b/drivers/Makefile
> @@ -86,6 +86,7 @@ obj-$(CONFIG_MTD) += mtd/
> obj-$(CONFIG_SPI) += spi/
> obj-$(CONFIG_SPMI) += spmi/
> obj-$(CONFIG_HSI) += hsi/
> +obj-$(CONFIG_SLIMBUS) += slimbus/
> obj-y += net/
> obj-$(CONFIG_ATM) += atm/
> obj-$(CONFIG_FUSION) += message/
> diff --git a/drivers/slimbus/Kconfig b/drivers/slimbus/Kconfig
> new file mode 100644
> index 0000000..f0b118a
> --- /dev/null
> +++ b/drivers/slimbus/Kconfig
> @@ -0,0 +1,11 @@
> +#
> +# SLIMBUS driver configuration
> +#
> +menuconfig SLIMBUS
> + tristate "Slimbus support"
> + help
> + Slimbus is standard interface between System-on-Chip and audio codec,
> + and other peripheral components in typical embedded systems.
> +
> + If unsure, choose N.
> +
> diff --git a/drivers/slimbus/Makefile b/drivers/slimbus/Makefile
> new file mode 100644
> index 0000000..f580704
> --- /dev/null
> +++ b/drivers/slimbus/Makefile
> @@ -0,0 +1,5 @@
> +#
> +# Makefile for kernel slimbus framework.
> +#
> +obj-$(CONFIG_SLIMBUS) += slimbus.o
> +slimbus-y := slim-core.o
> diff --git a/drivers/slimbus/slim-core.c b/drivers/slimbus/slim-core.c
> new file mode 100644
> index 0000000..de3ef79
> --- /dev/null
> +++ b/drivers/slimbus/slim-core.c
> @@ -0,0 +1,695 @@
> +/* Copyright (c) 2011-2017, The Linux Foundation. All rights reserved.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 and
> + * only version 2 as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/errno.h>
> +#include <linux/slab.h>
> +#include <linux/init.h>
> +#include <linux/completion.h>
> +#include <linux/idr.h>
> +#include <linux/pm_runtime.h>
> +#include <linux/slimbus.h>
> +#include <linux/of.h>
> +#include <linux/of_device.h>
> +
> +static DEFINE_MUTEX(slim_lock);
> +static DEFINE_IDR(ctrl_idr);
> +
> +static bool slim_eaddr_equal(struct slim_eaddr *a, struct slim_eaddr *b)
> +{
> +
> + return (a->manf_id == b->manf_id &&
> + a->prod_code == b->prod_code &&
> + a->dev_index == b->dev_index &&
> + a->instance == b->instance);
> +}
> +
> +static const struct slim_device_id *slim_match(const struct slim_device_id *id,
> + const struct slim_device *sbdev)
> +{
> + while (id->manf_id != 0 || id->prod_code != 0) {
> + if (id->manf_id == sbdev->e_addr.manf_id &&
> + id->prod_code == sbdev->e_addr.prod_code &&
> + id->dev_index == sbdev->e_addr.dev_index)
> + return id;
> + id++;
> + }
> + return NULL;
> +}
> +
> +static int slim_device_match(struct device *dev, struct device_driver *drv)
> +{
> + struct slim_device *sbdev = to_slim_device(dev);
> + struct slim_driver *sbdrv = to_slim_driver(drv);
> +
> + /* Attempt an OF style match first */
> + if (of_driver_match_device(dev, drv))
> + return 1;
> +
> + /* Then try to match against the id table */
> + if (sbdrv->id_table)
> + return slim_match(sbdrv->id_table, sbdev) != NULL;
> +
> + return 0;
> +}
> +
> +struct sb_report_wd {
> + struct work_struct wd;
> + struct slim_device *sbdev;
> + bool report;
> +};
> +
> +static void slim_report(struct work_struct *work)
> +{
> + struct slim_driver *sbdrv;
> + struct sb_report_wd *sbw = container_of(work, struct sb_report_wd, wd);
> + struct slim_device *sbdev = sbw->sbdev;
> +
> + mutex_lock(&sbdev->report_lock);
> + if (!sbdev->dev.driver)
> + goto report_exit;
> +
> + /* check if device-up or down needs to be called */
> + if ((!sbdev->reported && !sbdev->notified) ||
> + (sbdev->reported && sbdev->notified))
> + goto report_exit;
> +
> + sbdrv = to_slim_driver(sbdev->dev.driver);
> +
> + /**
> + * address no longer valid, means device reported absent, whereas
> + * address valid, means device reported present
> + */
> + if (sbdev->notified && !sbdev->reported) {
> + sbdev->notified = false;
> + if (sbdrv->device_down)
> + sbdrv->device_down(sbdev);
> + } else if (!sbdev->notified && sbdev->reported) {
> + sbdev->notified = true;
> + if (sbdrv->device_up)
> + sbdrv->device_up(sbdev);
> + }
> +report_exit:
> + mutex_unlock(&sbdev->report_lock);
> + kfree(sbw);
> +}
> +
> +/**
> + * Report callbacks(device_up, device_down) are implemented by slimbus-devices.
> + * The calls are scheduled into a workqueue to avoid holding up controller
> + * initialization/tear-down.
> + */
> +static void schedule_slim_report(struct slim_controller *ctrl,
> + struct slim_device *sb, bool report)
> +{
> + struct sb_report_wd *sbw;
> +
> + dev_dbg(&ctrl->dev, "report:%d for slave:%s\n", report, sb->name);
> +
> + sbw = kmalloc(sizeof(*sbw), GFP_KERNEL);
> + if (!sbw)
> + return;
> +
> + INIT_WORK(&sbw->wd, slim_report);
> + sbw->sbdev = sb;
> + sbw->report = report;
> + if (!queue_work(ctrl->wq, &sbw->wd)) {
> + dev_err(&ctrl->dev, "failed to queue report:%d slave:%s\n",
> + report, sb->name);
> + kfree(sbw);
> + }
> +}
> +
> +static int slim_device_probe(struct device *dev)
> +{
> + struct slim_device *sbdev;
> + struct slim_driver *sbdrv;
> + int status = 0;
> +
> + sbdev = to_slim_device(dev);
> + sbdrv = to_slim_driver(dev->driver);
> +
> + sbdev->driver = sbdrv;
> +
> + if (sbdrv->probe)
> + status = sbdrv->probe(sbdev);
> +
> + if (status)
> + sbdev->driver = NULL;
> + else if (sbdrv->device_up)
> + schedule_slim_report(sbdev->ctrl, sbdev, true);
> +
> + return status;
> +}
> +
> +static int slim_device_remove(struct device *dev)
> +{
> + struct slim_device *sbdev;
> + struct slim_driver *sbdrv;
> + int status = 0;
> +
> + sbdev = to_slim_device(dev);
> + if (!dev->driver)
> + return 0;
> +
> + sbdrv = to_slim_driver(dev->driver);
> + if (sbdrv->remove)
> + status = sbdrv->remove(sbdev);
> +
> + mutex_lock(&sbdev->report_lock);
> + sbdev->notified = false;
> + if (status == 0)
> + sbdev->driver = NULL;
> + mutex_unlock(&sbdev->report_lock);
> + return status;
> +}
> +
> +struct bus_type slimbus_type = {
> + .name = "slimbus",
> + .match = slim_device_match,
> + .probe = slim_device_probe,
> + .remove = slim_device_remove,
> +};
> +EXPORT_SYMBOL_GPL(slimbus_type);
> +
> +/**
> + * slim_driver_register: Client driver registration with slimbus
> + * @drv:Client driver to be associated with client-device.
> + * @owner: owning module/driver
> + * This API will register the client driver with the slimbus
> + * It is called from the driver's module-init function.
> + */
> +int __slim_driver_register(struct slim_driver *drv, struct module *owner)
> +{
> + drv->driver.bus = &slimbus_type;
> + drv->driver.owner = owner;
> + return driver_register(&drv->driver);
> +}
> +EXPORT_SYMBOL_GPL(__slim_driver_register);
> +
> +/**
> + * slim_driver_unregister: Undo effect of slim_driver_register
> + * @drv: Client driver to be unregistered
> + */
> +void slim_driver_unregister(struct slim_driver *drv)
> +{
> + if (drv)
> + driver_unregister(&drv->driver);
> +}
> +EXPORT_SYMBOL_GPL(slim_driver_unregister);
> +
> +static struct slim_controller *slim_ctrl_get(struct slim_controller *ctrl)
> +{
> + if (!ctrl || !get_device(&ctrl->dev))
> + return NULL;
> +
> + return ctrl;
> +}
> +
> +static void slim_ctrl_put(struct slim_controller *ctrl)
> +{
> + if (ctrl)
> + put_device(&ctrl->dev);
> +}
> +
> +static void slim_dev_release(struct device *dev)
> +{
> + struct slim_device *sbdev = to_slim_device(dev);
> +
> + slim_ctrl_put(sbdev->ctrl);
> + kfree(sbdev->name);
> + kfree(sbdev);
> +}
> +
> +static int slim_add_device(struct slim_controller *ctrl,
> + struct slim_device *sbdev)
> +{
> + sbdev->dev.bus = &slimbus_type;
> + sbdev->dev.parent = &ctrl->dev;
> + sbdev->dev.release = slim_dev_release;
> + sbdev->dev.driver = NULL;
> + sbdev->ctrl = ctrl;
> +
> + slim_ctrl_get(ctrl);
> + sbdev->name = kasprintf(GFP_KERNEL, "%x:%x:%x:%x",
> + sbdev->e_addr.manf_id,
> + sbdev->e_addr.prod_code,
> + sbdev->e_addr.dev_index,
> + sbdev->e_addr.instance);
> + if (!sbdev->name)
> + return -ENOMEM;
> +
> + dev_set_name(&sbdev->dev, "%s", sbdev->name);
> + mutex_init(&sbdev->report_lock);
> +
> + /* probe slave on this controller */
> + return device_register(&sbdev->dev);
> +}
> +
> +/* Helper to get hex Manufacturer ID and Product id from compatible */
> +static unsigned long str2hex(unsigned char *str)
> +{
> + int value = 0;
> +
> + while (*str) {
> + char c = *str++;
> +
> + value = value << 4;
> + if (c >= '0' && c <= '9')
> + value |= (c - '0');
> + if (c >= 'a' && c <= 'f')
> + value |= (c - 'a' + 10);
> +
> + }
> +
> + return value;
> +}
> +
> +/* OF helpers for SLIMbus */
> +static void of_register_slim_devices(struct slim_controller *ctrl)
> +{
> + struct device *dev = &ctrl->dev;
> + struct device_node *node;
> +
> + if (!ctrl->dev.of_node)
> + return;
> +
> + for_each_child_of_node(ctrl->dev.of_node, node) {
> + struct slim_device *slim;
> + const char *compat = NULL;
> + char *p, *tok;
> + int reg[2], ret;
> +
> + slim = kzalloc(sizeof(*slim), GFP_KERNEL);
> + if (!slim)
> + continue;
> +
> + slim->dev.of_node = of_node_get(node);
> +
> + compat = of_get_property(node, "compatible", NULL);
> + if (!compat)
> + continue;
> +
> + p = kasprintf(GFP_KERNEL, "%s", compat + strlen("slim"));
> +
> + tok = strsep(&p, ",");
> + if (!tok) {
> + dev_err(dev, "No valid Manufacturer ID found\n");
> + kfree(p);
> + continue;
> + }
> + slim->e_addr.manf_id = str2hex(tok);
> +
> + tok = strsep(&p, ",");
> + if (!tok) {
> + dev_err(dev, "No valid Product ID found\n");
> + kfree(p);
> + continue;
> + }
> + slim->e_addr.prod_code = str2hex(tok);
> + kfree(p);
> +
> + ret = of_property_read_u32_array(node, "reg", reg, 2);
> + if (ret) {
> + dev_err(dev, "Device and Instance id not found:%d\n",
> + ret);
> + continue;
> + }
> + slim->e_addr.dev_index = reg[0];
> + slim->e_addr.instance = reg[1];
> +
> + ret = slim_add_device(ctrl, slim);
> + if (ret)
> + dev_err(dev, "of_slim device register err:%d\n", ret);
> + }
> +}
> +
> +/**
> + * slim_register_controller: Controller bring-up and registration.
> + * @ctrl: Controller to be registered.
> + * A controller is registered with the framework using this API.
> + * If devices on a controller were registered before controller,
> + * this will make sure that they get probed when controller is up
> + */
> +int slim_register_controller(struct slim_controller *ctrl)
> +{
> + int id, ret = 0;
> +
> + mutex_lock(&slim_lock);
> + id = idr_alloc(&ctrl_idr, ctrl, ctrl->nr, -1, GFP_KERNEL);
> + mutex_unlock(&slim_lock);
> +
> + if (id < 0)
> + return id;
> +
> + ctrl->nr = id;
> +
> + dev_set_name(&ctrl->dev, "sb-%d", ctrl->nr);
> + ctrl->num_dev = 0;
> +
> + if (!ctrl->min_cg)
> + ctrl->min_cg = SLIM_MIN_CLK_GEAR;
> + if (!ctrl->max_cg)
> + ctrl->max_cg = SLIM_MAX_CLK_GEAR;
> +
> + mutex_init(&ctrl->m_ctrl);
> + ret = device_register(&ctrl->dev);
> + if (ret)
> + goto dev_reg_failed;
> +
> + dev_dbg(&ctrl->dev, "Bus [%s] registered:dev:%p\n",
> + ctrl->name, &ctrl->dev);
> +
> + ctrl->wq = create_singlethread_workqueue(dev_name(&ctrl->dev));
> + if (!ctrl->wq)
> + goto err_workq_failed;
> +
> + of_register_slim_devices(ctrl);
> +
> + return 0;
> +
> +err_workq_failed:
> + device_unregister(&ctrl->dev);
> +dev_reg_failed:
> + mutex_lock(&slim_lock);
> + idr_remove(&ctrl_idr, ctrl->nr);
> + mutex_unlock(&slim_lock);
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(slim_register_controller);
> +
> +/* slim_remove_device: Remove the effect of slim_add_device() */
> +static void slim_remove_device(struct slim_device *sbdev)
> +{
> + device_unregister(&sbdev->dev);
> +}
> +
> +static int slim_ctrl_remove_device(struct device *dev, void *null)
> +{
> + slim_remove_device(to_slim_device(dev));
> + return 0;
> +}
> +
> +/**
> + * slim_del_controller: Controller tear-down.
> + * @ctrl: Controller to tear-down.
> + */
> +int slim_del_controller(struct slim_controller *ctrl)
> +{
> + struct slim_controller *found;
> +
> + /* First make sure that this bus was added */
> + mutex_lock(&slim_lock);
> + found = idr_find(&ctrl_idr, ctrl->nr);
> + mutex_unlock(&slim_lock);
> + if (found != ctrl)
> + return -EINVAL;
> +
> + /* Remove all clients */
> + device_for_each_child(&ctrl->dev, NULL, slim_ctrl_remove_device);
> +
> +
> + destroy_workqueue(ctrl->wq);
> +
> + /* free bus id */
> + mutex_lock(&slim_lock);
> + idr_remove(&ctrl_idr, ctrl->nr);
> + mutex_unlock(&slim_lock);
> +
> + device_unregister(&ctrl->dev);
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(slim_del_controller);
> +
> +/**
> + * slim_report_absent: Controller calls this function when a device
> + * reports absent, OR when the device cannot be communicated with
> + * @sbdev: Device that cannot be reached, or sent report absent
> + */
> +void slim_report_absent(struct slim_device *sbdev)
> +{
> + struct slim_controller *ctrl;
> + int i;
> +
> + if (!sbdev)
> + return;
> + ctrl = sbdev->ctrl;
> + if (!ctrl)
> + return;
> +
> + /* invalidate logical addresses */
> + mutex_lock(&ctrl->m_ctrl);
> + for (i = 0; i < ctrl->num_dev; i++) {
> + if (sbdev->laddr == ctrl->addrt[i].laddr)
> + ctrl->addrt[i].valid = false;
> + }
> + mutex_unlock(&ctrl->m_ctrl);
> +
> + mutex_lock(&sbdev->report_lock);
> + sbdev->reported = false;
> + schedule_slim_report(ctrl, sbdev, false);
> + mutex_unlock(&sbdev->report_lock);
> +}
> +EXPORT_SYMBOL_GPL(slim_report_absent);
> +
> +static int slim_boot_child(struct device *dev, void *unused)
> +{
> + struct slim_driver *sbdrv;
> + struct slim_device *sbdev = to_slim_device(dev);
> +
> + if (sbdev && sbdev->dev.driver) {
> + sbdrv = to_slim_driver(sbdev->dev.driver);
> + if (sbdrv->boot_device)
> + sbdrv->boot_device(sbdev);
> + }
> + return 0;
> +}
> +
> +static int slim_match_dev(struct device *dev, void *data)
> +{
> + struct slim_eaddr *e_addr = data;
> + struct slim_device *slim = to_slim_device(dev);
> +
> + return slim_eaddr_equal(&slim->e_addr, e_addr);
> +}
> +
> +/**
> + * slim_framer_booted: This function is called by controller after the active
> + * framer has booted (using Bus Reset sequence, or after it has shutdown and has
> + * come back up).
> + * @ctrl: Controller associated with this framer
> + * Components, devices on the bus may be in undefined state,
> + * and this function triggers their drivers to do the needful
> + * to bring them back in Reset state so that they can acquire sync, report
> + * present and be operational again.
> + */
> +void slim_framer_booted(struct slim_controller *ctrl)
> +{
> + if (!ctrl)
> + return;
> +
> + device_for_each_child(&ctrl->dev, NULL, slim_boot_child);
> +}
> +EXPORT_SYMBOL_GPL(slim_framer_booted);
> +
> +/**
> + * slim_query_device: Query and get handle to a device.
> + * @ctrl: Controller on which this device will be added/queried
> + * @e_addr: Enumeration address of the device to be queried
> + * Returns pointer to a device if it has already reported. Creates a new
> + * device and returns pointer to it if the device has not yet enumerated.
> + */
> +struct slim_device *slim_query_device(struct slim_controller *ctrl,
> + struct slim_eaddr *e_addr)
> +{
> + struct device *dev;
> + struct slim_device *slim = NULL;
> +
> + dev = device_find_child(&ctrl->dev, e_addr, slim_match_dev);
> + if (dev) {
> + slim = to_slim_device(dev);
> + return slim;
> + }
> +
> + slim = kzalloc(sizeof(struct slim_device), GFP_KERNEL);
> + if (IS_ERR(slim))
> + return NULL;
> +
> + slim->e_addr = *e_addr;
> + if (slim_add_device(ctrl, slim) != 0) {
> + kfree(slim);
> + return NULL;
> + }
> + return slim;
> +}
> +EXPORT_SYMBOL_GPL(slim_query_device);
> +
> +static int ctrl_getaddr_entry(struct slim_controller *ctrl,
> + struct slim_eaddr *eaddr, u8 *entry)
> +{
> + int i;
> +
> + for (i = 0; i < ctrl->num_dev; i++) {
> + if (ctrl->addrt[i].valid &&
> + slim_eaddr_equal(&ctrl->addrt[i].eaddr, eaddr)) {
> + *entry = i;
> + return 0;
> + }
> + }
> + return -ENXIO;
> +}
> +
> +/**
> + * slim_assign_laddr: Assign logical address to a device enumerated.
> + * @ctrl: Controller with which device is enumerated.
> + * @e_addr: Enumeration address of the device.
> + * @laddr: Return logical address (if valid flag is false)
> + * @valid: true if laddr holds a valid address that controller wants to
> + * set for this enumeration address. Otherwise framework sets index into
> + * address table as logical address.
> + * Called by controller in response to REPORT_PRESENT. Framework will assign
> + * a logical address to this enumeration address.
> + * Function returns -EXFULL to indicate that all logical addresses are already
> + * taken.
> + */
> +int slim_assign_laddr(struct slim_controller *ctrl, struct slim_eaddr *e_addr,
> + u8 *laddr, bool valid)
> +{
> + int ret;
> + u8 i = 0;
> + bool exists = false;
> + struct slim_device *slim;
> + struct slim_addrt *temp;
> +
> + mutex_lock(&ctrl->m_ctrl);
> + /* already assigned */
> + if (ctrl_getaddr_entry(ctrl, e_addr, &i) == 0) {
> + *laddr = ctrl->addrt[i].laddr;
> + exists = true;
> + } else {
> + if (ctrl->num_dev >= (SLIM_LA_MANAGER - 1)) {
> + ret = -EXFULL;
> + goto ret_assigned_laddr;
> + }
> + for (i = 0; i < ctrl->num_dev; i++) {
> + if (ctrl->addrt[i].valid == false)
> + break;
> + }
> + if (i == ctrl->num_dev) {
> + temp = krealloc(ctrl->addrt,
> + (ctrl->num_dev + 1) *
> + sizeof(struct slim_addrt),
> + GFP_KERNEL);
> + if (!temp) {
> + ret = -ENOMEM;
> + goto ret_assigned_laddr;
> + }
> + ctrl->addrt = temp;
> + ctrl->num_dev++;
> + }
> + ctrl->addrt[i].eaddr = *e_addr;
> + ctrl->addrt[i].valid = true;
> +
> + /* Preferred address is index into table */
> + if (!valid)
> + *laddr = i;
> + }
> +
> + ret = ctrl->set_laddr(ctrl, &ctrl->addrt[i].eaddr, *laddr);
> + if (ret) {
> + ctrl->addrt[i].valid = false;
> + goto ret_assigned_laddr;
> + }
> + ctrl->addrt[i].laddr = *laddr;
> +
> +ret_assigned_laddr:
> + mutex_unlock(&ctrl->m_ctrl);
> + if (exists || ret)
> + return ret;
> +
> + dev_info(&ctrl->dev, "setting slimbus l-addr:%x, ea:%x,%x,%x,%x\n",
> + *laddr, e_addr->manf_id, e_addr->prod_code,
> + e_addr->dev_index, e_addr->instance);
> +
> + /**
> + * Add this device to list of devices on this controller if it's
> + * not already present
> + */
> + slim = slim_query_device(ctrl, e_addr);
> + if (!slim) {
> + ret = -ENODEV;
> + } else {
> + struct slim_driver *sbdrv;
> +
> + slim->laddr = *laddr;
> + mutex_lock(&slim->report_lock);
> + slim->reported = true;
> + if (slim->dev.driver) {
> + sbdrv = to_slim_driver(slim->dev.driver);
> + if (sbdrv->device_up)
> + schedule_slim_report(ctrl, slim, true);
> + }
> + mutex_unlock(&slim->report_lock);
> + }
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(slim_assign_laddr);
> +
> +/**
> + * slim_get_logical_addr: Return the logical address of a slimbus device.
> + * @sb: client handle requesting the address.
> + * @e_addr: Enumeration address of the device.
> + * @laddr: output buffer to store the address
> + * context: can sleep
> + * -EINVAL is returned in case of invalid parameters, and -ENXIO is returned if
> + * the device with this enumeration address is not found.
> + */
> +int slim_get_logical_addr(struct slim_device *sb, struct slim_eaddr *e_addr,
> + u8 *laddr)
> +{
> + int ret;
> + u8 entry;
> + struct slim_controller *ctrl = sb->ctrl;
> +
> + if (!ctrl || !laddr || !e_addr)
> + return -EINVAL;
> +
> + mutex_lock(&ctrl->m_ctrl);
> + ret = ctrl_getaddr_entry(ctrl, e_addr, &entry);
> + if (!ret)
> + *laddr = ctrl->addrt[entry].laddr;
> + mutex_unlock(&ctrl->m_ctrl);
> +
> + if (ret == -ENXIO && ctrl->get_laddr) {
> + ret = ctrl->get_laddr(ctrl, e_addr, laddr);
> + if (!ret)
> + ret = slim_assign_laddr(ctrl, e_addr, laddr, true);
> + }
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(slim_get_logical_addr);
> +
> +static void __exit slimbus_exit(void)
> +{
> + bus_unregister(&slimbus_type);
> +}
> +module_exit(slimbus_exit);
> +
> +static int __init slimbus_init(void)
> +{
> + return bus_register(&slimbus_type);
> +}
> +postcore_initcall(slimbus_init);
> +
> +MODULE_LICENSE("GPL v2");
> +MODULE_VERSION("0.1");
> +MODULE_DESCRIPTION("Slimbus module");
> diff --git a/include/linux/mod_devicetable.h b/include/linux/mod_devicetable.h
> index 694cebb..015e5f6 100644
> --- a/include/linux/mod_devicetable.h
> +++ b/include/linux/mod_devicetable.h
> @@ -448,6 +448,19 @@ struct spi_device_id {
> kernel_ulong_t driver_data; /* Data private to the driver */
> };
>
> +/* SLIMbus */
> +
> +#define SLIMBUS_NAME_SIZE 32
> +#define SLIMBUS_MODULE_PREFIX "slim:"
> +
> +struct slim_device_id {
> + __u16 manf_id, prod_code;
> + __u8 dev_index, instance;
> +
> + /* Data private to the driver */
> + kernel_ulong_t driver_data;
> +};
> +
> #define SPMI_NAME_SIZE 32
> #define SPMI_MODULE_PREFIX "spmi:"
>
> diff --git a/include/linux/slimbus.h b/include/linux/slimbus.h
> new file mode 100644
> index 0000000..b5064b6
> --- /dev/null
> +++ b/include/linux/slimbus.h
> @@ -0,0 +1,299 @@
> +/* Copyright (c) 2011-2017, The Linux Foundation. All rights reserved.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 and
> + * only version 2 as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + */
> +
> +#ifndef _LINUX_SLIMBUS_H
> +#define _LINUX_SLIMBUS_H
> +#include <linux/module.h>
> +#include <linux/device.h>
> +#include <linux/mutex.h>
> +#include <linux/mod_devicetable.h>
> +
> +/**
> + * Interfaces between SLIMbus manager drivers, SLIMbus client drivers, and
> + * SLIMbus infrastructure.
> + */
> +
> +extern struct bus_type slimbus_type;
> +
> +/* Standard values per SLIMbus spec needed by controllers and devices */
> +#define SLIM_CL_PER_SUPERFRAME 6144
> +#define SLIM_CL_PER_SUPERFRAME_DIV8 (SLIM_CL_PER_SUPERFRAME >> 3)
> +#define SLIM_MAX_CLK_GEAR 10
> +#define SLIM_MIN_CLK_GEAR 1
> +#define SLIM_CL_PER_SL 4
> +#define SLIM_SL_PER_SUPERFRAME (SLIM_CL_PER_SUPERFRAME >> 2)
> +#define SLIM_FRM_SLOTS_PER_SUPERFRAME 16
> +#define SLIM_GDE_SLOTS_PER_SUPERFRAME 2
> +
> +struct slim_controller;
> +struct slim_device;
> +
> +/**
> + * struct slim_eaddr: Enumeration address for a slimbus device
> + * @manf_id: Manufacturer Id for the device
> + * @prod_code: Product code
> + * @dev_index: Device index
> + * @instance: Instance value
> + */
> +struct slim_eaddr {
> + u16 manf_id;
> + u16 prod_code;
> + u8 dev_index;
> + u8 instance;
> +};
> +
> +/**
> + * struct slim_framer - Represents Slimbus framer.
> + * Every controller may have multiple framers. There is 1 active framer device
> + * responsible for clocking the bus.
> + * Manager is responsible for framer hand-over.
> + * @dev: Driver model representation of the device.
> + * @e_addr: Enumeration address of the framer.
> + * @rootfreq: Root Frequency at which the framer can run. This is maximum
> + * frequency ('clock gear 10') at which the bus can operate.
> + * @superfreq: Superframes per root frequency. Every frame is 6144 bits.
> + */
> +struct slim_framer {
> + struct device dev;
> + struct slim_eaddr e_addr;
> + int rootfreq;
> + int superfreq;
> +};
> +
> +#define to_slim_framer(d) container_of(d, struct slim_framer, dev)
> +
> +/**
> + * struct slim_addrt: slimbus address used internally by the slimbus framework.
> + * @valid: If the device is present. Valid is set to false when device reports
> + * absent.
> + * @eaddr: Enumeration address
> + * @laddr: It is possible that controller will set a predefined logical address
> + * rather than the one assigned by framework. (i.e. logical address may
> + * not be same as index into this table). This entry will store the
> + * logical address value for this enumeration address.
> + */
> +struct slim_addrt {
> + bool valid;
> + struct slim_eaddr eaddr;
> + u8 laddr;
> +};
> +
> +/* SLIMbus message types. Related to interpretation of message code. */
> +#define SLIM_MSG_MT_CORE 0x0
> +#define SLIM_MSG_MT_DEST_REFERRED_CLASS 0x1
> +#define SLIM_MSG_MT_DEST_REFERRED_USER 0x2
> +#define SLIM_MSG_MT_SRC_REFERRED_CLASS 0x5
> +#define SLIM_MSG_MT_SRC_REFERRED_USER 0x6
> +
> +/* SLIMbus core type Message Codes. */
> +/* Device management messages used by this framework */
> +#define SLIM_MSG_MC_REPORT_PRESENT 0x1
> +#define SLIM_MSG_MC_ASSIGN_LOGICAL_ADDRESS 0x2
> +#define SLIM_MSG_MC_REPORT_ABSENT 0xF
> +
> +/* Destination type Values */
> +#define SLIM_MSG_DEST_LOGICALADDR 0
> +#define SLIM_MSG_DEST_ENUMADDR 1
> +#define SLIM_MSG_DEST_BROADCAST 3
> +
> +/**
> + * struct slim_controller: Controls every instance of SLIMbus
> + * (similar to 'master' on SPI)
> + * 'Manager device' is responsible for device management, bandwidth
> + * allocation, channel setup, and port associations per channel.
> + * Device management means Logical address assignment/removal based on
> + * enumeration (report-present, report-absent) if a device.
> + * Bandwidth allocation is done dynamically by the manager based on active
> + * channels on the bus, message-bandwidth requests made by slimbus devices.
> + * Based on current bandwidth usage, manager chooses a frequency to run
> + * the bus at (in steps of 'clock-gear', 1 through 10, each clock gear
> + * representing twice the frequency than the previous gear).
> + * Manager is also responsible for entering (and exiting) low-power-mode
> + * (known as 'clock pause').
> + * Manager can do handover of framer if there are multiple framers on the
> + * bus and a certain usecase warrants using certain framer to avoid keeping
> + * previous framer being powered-on.
> + *
> + * Controller here performs duties of the manager device, and 'interface
> + * device'. Interface device is responsible for monitoring the bus and
> + * reporting information such as loss-of-synchronization, data
> + * slot-collision.
> + * @dev: Device interface to this driver
> + * @nr: Board-specific number identifier for this controller/bus
> + * @list: Link with other slimbus controllers
> + * @name: Name for this controller
> + * @min_cg: Minimum clock gear supported by this controller (default value: 1)
> + * @max_cg: Maximum clock gear supported by this controller (default value: 10)
> + * @clkgear: Current clock gear in which this bus is running
> + * @a_framer: Active framer which is clocking the bus managed by this controller
> + * @m_ctrl: Mutex protecting controller data structures
> + * @addrt: Logical address table
> + * @num_dev: Number of active slimbus slaves on this bus
> + * @wq: Workqueue per controller used to notify devices when they report present
> + * @xfer_msg: Transfer a message on this controller (this can be a broadcast
> + * control/status message like data channel setup, or a unicast message
> + * like value element read/write.
xfer_msg element is not present in structure.
> + * @set_laddr: Setup logical address at laddr for the slave with elemental
> + * address e_addr. Drivers implementing controller will be expected to
> + * send unicast message to this device with its logical address.
> + * @get_laddr: It is possible that controller needs to set fixed logical
> + * address table and get_laddr can be used in that case so that controller
> + * can do this assignment.
> + */
> +struct slim_controller {
> + struct device dev;
> + unsigned int nr;
> + char name[SLIMBUS_NAME_SIZE];
> + int min_cg;
> + int max_cg;
> + int clkgear;
> + struct slim_framer *a_framer;
> + struct mutex m_ctrl;
> + struct slim_addrt *addrt;
> + u8 num_dev;
> + struct workqueue_struct *wq;
> + int (*set_laddr)(struct slim_controller *ctrl,
> + struct slim_eaddr *ea, u8 laddr);
> + int (*get_laddr)(struct slim_controller *ctrl,
> + struct slim_eaddr *ea, u8 *laddr);
> +};
> +
> +#define to_slim_controller(d) container_of(d, struct slim_controller, dev)
> +
> +/**
> + * struct slim_driver: Slimbus 'generic device' (slave) device driver
> + * (similar to 'spi_device' on SPI)
> + * @probe: Binds this driver to a slimbus device.
> + * @remove: Unbinds this driver from the slimbus device.
> + * @shutdown: Standard shutdown callback used during powerdown/halt.
> + * @suspend: Standard suspend callback used during system suspend
> + * @resume: Standard resume callback used during system resume
> + * @device_up: This callback is called when the device reports present and
> + * gets a logical address assigned to it
> + * @device_down: This callback is called when device reports absent, or the
> + * bus goes down. Device will report present when bus is up and
> + * device_up callback will be called again when that happens
> + * @boot_device: This callback is called after framer is booted.
> + * Driver should do the needful to boot the device,
> + * so that device acquires sync and be operational.
> + * @driver: Slimbus device drivers should initialize name and owner field of
> + * this structure
> + * @id_table: List of slimbus devices supported by this driver
> + */
> +struct slim_driver {
> + int (*probe)(struct slim_device *sl);
> + int (*remove)(struct slim_device *sl);
> + void (*shutdown)(struct slim_device *sl);
> + int (*suspend)(struct slim_device *sl,
> + pm_message_t pmesg);
> + int (*resume)(struct slim_device *sl);
> + int (*device_up)(struct slim_device *sl);
> + int (*device_down)(struct slim_device *sl);
> + int (*boot_device)(struct slim_device *sl);
> +
> + struct device_driver driver;
> + const struct slim_device_id *id_table;
> +};
> +
> +#define to_slim_driver(d) container_of(d, struct slim_driver, driver)
> +
> +/**
> + * Client/device handle (struct slim_device):
> + * ------------------------------------------
> + * This is the client/device handle returned when a slimbus
> + * device is registered with a controller.
> + * Pointer to this structure is used by client-driver as a handle.
> + * @dev: Driver model representation of the device.
> + * @name: Name of driver to use with this device.
> + * @e_addr: Enumeration address of this device.
> + * @driver: Device's driver. Pointer to access routines.
> + * @ctrl: Slimbus controller managing the bus hosting this device.
> + * @laddr: 1-byte Logical address of this device.
> + * @reported: Flag to indicate whether this device reported present. The flag
> + * is set when device reports present, and is reset when it reports
> + * absent. This flag alongwith notified flag below is used to call
> + * device_up, or device_down callbacks for driver of this device.
> + * @notified: Flag to indicate whether this device has been notified. The
> + * device may report present multiple times, but should be notified only
> + * first time it has reported present.
> + * @report_lock: Lock to protect reporting and notification for this device
> + */
> +struct slim_device {
> + struct device dev;
> + char *name;
> + struct slim_eaddr e_addr;
> + struct slim_driver *driver;
> + struct slim_controller *ctrl;
> + u8 laddr;
> + bool reported;
> + bool notified;
> + struct mutex report_lock;
> +};
> +
> +#define to_slim_device(d) container_of(d, struct slim_device, dev)
> +
> +/* Manager's logical address is set to 0xFF per spec */
> +#define SLIM_LA_MANAGER 0xFF
> +
> +int slim_get_logical_addr(struct slim_device *sb,
> + struct slim_eaddr *e_addr, u8 *laddr);
> +
> +/*
> + * use a macro to avoid include chaining to get THIS_MODULE
> + */
> +#define slim_driver_register(drv) \
> + __slim_driver_register(drv, THIS_MODULE)
> +
> +int __slim_driver_register(struct slim_driver *drv, struct module *owner);
> +
> +void slim_driver_unregister(struct slim_driver *drv);
> +
> +/**
> + * module_slim_driver() - Helper macro for registering a slimbus driver
> + * @__slimbus_driver: slimbus_driver struct
> + *
> + * Helper macro for slimbus drivers which do not do anything special in module
> + * init/exit. This eliminates a lot of boilerplate. Each module may only
> + * use this macro once, and calling it replaces module_init() and module_exit()
> + */
> +#define module_slim_driver(__slim_driver) \
> + module_driver(__slim_driver, slim_driver_register, \
> + slim_driver_unregister)
> +
> +int slim_del_controller(struct slim_controller *ctrl);
> +int slim_assign_laddr(struct slim_controller *ctrl,
> + struct slim_eaddr *e_addr, u8 *laddr, bool valid);
> +void slim_report_absent(struct slim_device *sbdev);
> +void slim_framer_booted(struct slim_controller *ctrl);
> +int slim_register_controller(struct slim_controller *ctrl);
> +
> +static inline void *slim_get_ctrldata(const struct slim_controller *dev)
> +{
> + return dev_get_drvdata(&dev->dev);
> +}
> +
> +static inline void slim_set_ctrldata(struct slim_controller *dev, void *data)
> +{
> + dev_set_drvdata(&dev->dev, data);
> +}
> +
> +static inline void *slim_get_devicedata(const struct slim_device *dev)
> +{
> + return dev_get_drvdata(&dev->dev);
> +}
> +
> +static inline void slim_set_devicedata(struct slim_device *dev, void *data)
> +{
> + dev_set_drvdata(&dev->dev, data);
> +}
> +
> +#endif /* _LINUX_SLIMBUS_H */
> --
> 2.9.3
>
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