From: Sagar Dharia sdharia@codeaurora.org
Per SLIMbus specification, a reconfiguration sequence known as 'clock pause' needs to be broadcast over the bus while entering low- power mode. Clock-pause is initiated by the controller driver. To exit clock-pause, controller typically wakes up the framer device. Since wakeup precedure is controller-specific, framework calls it via controller's function pointer to invoke it.
Signed-off-by: Sagar Dharia sdharia@codeaurora.org Signed-off-by: Srinivas Kandagatla srinivas.kandagatla@linaro.org --- drivers/slimbus/Makefile | 2 +- drivers/slimbus/core.c | 16 ++++++ drivers/slimbus/messaging.c | 35 ++++++++++++- drivers/slimbus/sched.c | 121 ++++++++++++++++++++++++++++++++++++++++++++ drivers/slimbus/slimbus.h | 53 +++++++++++++++++++ 5 files changed, 225 insertions(+), 2 deletions(-) create mode 100644 drivers/slimbus/sched.c
diff --git a/drivers/slimbus/Makefile b/drivers/slimbus/Makefile index 568a14c7be78..cd6833ed521a 100644 --- a/drivers/slimbus/Makefile +++ b/drivers/slimbus/Makefile @@ -3,4 +3,4 @@ # Makefile for kernel SLIMbus framework. # obj-$(CONFIG_SLIMBUS) += slimbus.o -slimbus-y := core.o messaging.o +slimbus-y := core.o messaging.o sched.o diff --git a/drivers/slimbus/core.c b/drivers/slimbus/core.c index 1accb20ed5cd..4988a8f4d905 100644 --- a/drivers/slimbus/core.c +++ b/drivers/slimbus/core.c @@ -9,6 +9,7 @@ #include <linux/init.h> #include <linux/idr.h> #include <linux/of.h> +#include <linux/pm_runtime.h> #include <linux/slimbus.h> #include "slimbus.h"
@@ -218,6 +219,8 @@ int slim_register_controller(struct slim_controller *ctrl) ida_init(&ctrl->laddr_ida); idr_init(&ctrl->tid_idr); mutex_init(&ctrl->lock); + mutex_init(&ctrl->sched.m_reconf); + init_completion(&ctrl->sched.pause_comp);
dev_dbg(ctrl->dev, "Bus [%s] registered:dev:%p\n", ctrl->name, ctrl->dev); @@ -249,6 +252,8 @@ int slim_unregister_controller(struct slim_controller *ctrl) { /* Remove all clients */ device_for_each_child(ctrl->dev, NULL, slim_ctrl_remove_device); + /* Enter Clock Pause */ + slim_ctrl_clk_pause(ctrl, false, 0); ida_simple_remove(&ctrl_ida, ctrl->id);
return 0; @@ -416,6 +421,14 @@ int slim_device_report_present(struct slim_controller *ctrl, struct slim_device *sbdev; int ret;
+ ret = pm_runtime_get_sync(ctrl->dev); + + if (ctrl->sched.clk_state != SLIM_CLK_ACTIVE) { + dev_err(ctrl->dev, "slim ctrl not active,state:%d, ret:%d\n", + ctrl->sched.clk_state, ret); + goto slimbus_not_active; + } + sbdev = slim_get_device(ctrl, e_addr); if (IS_ERR(sbdev)) return -ENODEV; @@ -427,6 +440,9 @@ int slim_device_report_present(struct slim_controller *ctrl,
ret = slim_device_alloc_laddr(sbdev, true);
+slimbus_not_active: + pm_runtime_mark_last_busy(ctrl->dev); + pm_runtime_put_autosuspend(ctrl->dev); return ret; } EXPORT_SYMBOL_GPL(slim_device_report_present); diff --git a/drivers/slimbus/messaging.c b/drivers/slimbus/messaging.c index 031e67648d7c..755462a4c75e 100644 --- a/drivers/slimbus/messaging.c +++ b/drivers/slimbus/messaging.c @@ -4,6 +4,7 @@ */
#include <linux/slab.h> +#include <linux/pm_runtime.h> #include "slimbus.h"
/** @@ -46,6 +47,10 @@ void slim_msg_response(struct slim_controller *ctrl, u8 *reply, u8 tid, u8 len) memcpy(msg->rbuf, reply, len); if (txn->comp) complete(txn->comp); + + /* Remove runtime-pm vote now that response was received for TID txn */ + pm_runtime_mark_last_busy(ctrl->dev); + pm_runtime_put_autosuspend(ctrl->dev); } EXPORT_SYMBOL_GPL(slim_msg_response);
@@ -65,10 +70,29 @@ EXPORT_SYMBOL_GPL(slim_msg_response); int slim_do_transfer(struct slim_controller *ctrl, struct slim_msg_txn *txn) { DECLARE_COMPLETION_ONSTACK(done); - bool need_tid; + bool need_tid = false, clk_pause_msg = false; unsigned long flags; int ret, tid, timeout;
+ /* + * do not vote for runtime-PM if the transactions are part of clock + * pause sequence + */ + if (ctrl->sched.clk_state == SLIM_CLK_ENTERING_PAUSE && + (txn->mt == SLIM_MSG_MT_CORE && + txn->mc >= SLIM_MSG_MC_BEGIN_RECONFIGURATION && + txn->mc <= SLIM_MSG_MC_RECONFIGURE_NOW)) + clk_pause_msg = true; + + if (!clk_pause_msg) { + ret = pm_runtime_get_sync(ctrl->dev); + if (ctrl->sched.clk_state != SLIM_CLK_ACTIVE) { + dev_err(ctrl->dev, "ctrl wrong state:%d, ret:%d\n", + ctrl->sched.clk_state, ret); + goto slim_xfer_err; + } + } + need_tid = slim_tid_txn(txn->mt, txn->mc);
if (need_tid) { @@ -107,6 +131,15 @@ int slim_do_transfer(struct slim_controller *ctrl, struct slim_msg_txn *txn) dev_err(ctrl->dev, "Tx:MT:0x%x, MC:0x%x, LA:0x%x failed:%d\n", txn->mt, txn->mc, txn->la, ret);
+slim_xfer_err: + if (!clk_pause_msg && (!need_tid || ret == -ETIMEDOUT)) { + /* + * remove runtime-pm vote if this was TX only, or + * if there was error during this transaction + */ + pm_runtime_mark_last_busy(ctrl->dev); + pm_runtime_mark_last_busy(ctrl->dev); + } return ret; } EXPORT_SYMBOL_GPL(slim_do_transfer); diff --git a/drivers/slimbus/sched.c b/drivers/slimbus/sched.c new file mode 100644 index 000000000000..af84997d2742 --- /dev/null +++ b/drivers/slimbus/sched.c @@ -0,0 +1,121 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (c) 2011-2017, The Linux Foundation + */ + +#include <linux/errno.h> +#include "slimbus.h" + +/** + * slim_ctrl_clk_pause() - Called by slimbus controller to enter/exit + * 'clock pause' + * @ctrl: controller requesting bus to be paused or woken up + * @wakeup: Wakeup this controller from clock pause. + * @restart: Restart time value per spec used for clock pause. This value + * isn't used when controller is to be woken up. + * + * Slimbus specification needs this sequence to turn-off clocks for the bus. + * The sequence involves sending 3 broadcast messages (reconfiguration + * sequence) to inform all devices on the bus. + * To exit clock-pause, controller typically wakes up active framer device. + * This API executes clock pause reconfiguration sequence if wakeup is false. + * If wakeup is true, controller's wakeup is called. + * For entering clock-pause, -EBUSY is returned if a message txn in pending. + */ +int slim_ctrl_clk_pause(struct slim_controller *ctrl, bool wakeup, u8 restart) +{ + int i, ret = 0; + unsigned long flags; + struct slim_sched *sched = &ctrl->sched; + struct slim_val_inf msg = {0, 0, NULL, NULL}; + + DEFINE_SLIM_BCAST_TXN(txn, SLIM_MSG_MC_BEGIN_RECONFIGURATION, + 3, SLIM_LA_MANAGER, &msg); + + if (wakeup == false && restart > SLIM_CLK_UNSPECIFIED) + return -EINVAL; + + mutex_lock(&sched->m_reconf); + if (wakeup) { + if (sched->clk_state == SLIM_CLK_ACTIVE) { + mutex_unlock(&sched->m_reconf); + return 0; + } + + /* + * Fine-tune calculation based on clock gear, + * message-bandwidth after bandwidth management + */ + ret = wait_for_completion_timeout(&sched->pause_comp, + msecs_to_jiffies(100)); + if (!ret) { + mutex_unlock(&sched->m_reconf); + pr_err("Previous clock pause did not finish"); + return -ETIMEDOUT; + } + ret = 0; + + /* + * Slimbus framework will call controller wakeup + * Controller should make sure that it sets active framer + * out of clock pause + */ + if (sched->clk_state == SLIM_CLK_PAUSED && ctrl->wakeup) + ret = ctrl->wakeup(ctrl); + if (!ret) + sched->clk_state = SLIM_CLK_ACTIVE; + mutex_unlock(&sched->m_reconf); + + return ret; + } + + /* already paused */ + if (ctrl->sched.clk_state == SLIM_CLK_PAUSED) { + mutex_unlock(&sched->m_reconf); + return 0; + } + + spin_lock_irqsave(&ctrl->txn_lock, flags); + for (i = 0; i < SLIM_MAX_TIDS; i++) { + /* Pending response for a message */ + if (idr_find(&ctrl->tid_idr, i)) { + spin_unlock_irqrestore(&ctrl->txn_lock, flags); + mutex_unlock(&sched->m_reconf); + return -EBUSY; + } + } + spin_unlock_irqrestore(&ctrl->txn_lock, flags); + + sched->clk_state = SLIM_CLK_ENTERING_PAUSE; + + /* clock pause sequence */ + ret = slim_do_transfer(ctrl, &txn); + if (ret) + goto clk_pause_ret; + + txn.mc = SLIM_MSG_MC_NEXT_PAUSE_CLOCK; + txn.rl = 4; + msg.num_bytes = 1; + msg.wbuf = &restart; + ret = slim_do_transfer(ctrl, &txn); + if (ret) + goto clk_pause_ret; + + txn.mc = SLIM_MSG_MC_RECONFIGURE_NOW; + txn.rl = 3; + msg.num_bytes = 1; + msg.wbuf = NULL; + ret = slim_do_transfer(ctrl, &txn); + +clk_pause_ret: + if (ret) { + sched->clk_state = SLIM_CLK_ACTIVE; + } else { + sched->clk_state = SLIM_CLK_PAUSED; + complete(&sched->pause_comp); + } + mutex_unlock(&sched->m_reconf); + + return ret; +} +EXPORT_SYMBOL_GPL(slim_ctrl_clk_pause); diff --git a/drivers/slimbus/slimbus.h b/drivers/slimbus/slimbus.h index 0d40c2578c28..db089134f673 100644 --- a/drivers/slimbus/slimbus.h +++ b/drivers/slimbus/slimbus.h @@ -14,6 +14,16 @@ /* SLIMbus message types. Related to interpretation of message code. */ #define SLIM_MSG_MT_CORE 0x0
+/* Clock pause Reconfiguration messages */ +#define SLIM_MSG_MC_BEGIN_RECONFIGURATION 0x40 +#define SLIM_MSG_MC_NEXT_PAUSE_CLOCK 0x4A +#define SLIM_MSG_MC_RECONFIGURE_NOW 0x5F + +/* Clock pause values per SLIMbus spec */ +#define SLIM_CLK_FAST 0 +#define SLIM_CLK_CONST_PHASE 1 +#define SLIM_CLK_UNSPECIFIED 2 + /* Destination type Values */ #define SLIM_MSG_DEST_LOGICALADDR 0 #define SLIM_MSG_DEST_ENUMADDR 1 @@ -80,6 +90,42 @@ struct slim_msg_txn { #define DEFINE_SLIM_LDEST_TXN(name, mc, rl, la, msg) \ struct slim_msg_txn name = { rl, 0, mc, SLIM_MSG_DEST_LOGICALADDR, 0,\ 0, la, msg, } + +#define DEFINE_SLIM_BCAST_TXN(name, mc, rl, la, msg) \ + struct slim_msg_txn name = { rl, 0, mc, SLIM_MSG_DEST_BROADCAST, 0,\ + 0, la, msg, } +/** + * enum slim_clk_state: SLIMbus controller's clock state used internally for + * maintaining current clock state. + * @SLIM_CLK_ACTIVE: SLIMbus clock is active + * @SLIM_CLK_ENTERING_PAUSE: SLIMbus clock pause sequence is being sent on the + * bus. If this succeeds, state changes to SLIM_CLK_PAUSED. If the + * transition fails, state changes back to SLIM_CLK_ACTIVE + * @SLIM_CLK_PAUSED: SLIMbus controller clock has paused. + */ +enum slim_clk_state { + SLIM_CLK_ACTIVE, + SLIM_CLK_ENTERING_PAUSE, + SLIM_CLK_PAUSED, +}; + +/** + * struct slim_sched: Framework uses this structure internally for scheduling. + * @clk_state: Controller's clock state from enum slim_clk_state + * @pause_comp: Signals completion of clock pause sequence. This is useful when + * client tries to call SLIMbus transaction when controller is entering + * clock pause. + * @m_reconf: This mutex is held until current reconfiguration (data channel + * scheduling, message bandwidth reservation) is done. Message APIs can + * use the bus concurrently when this mutex is held since elemental access + * messages can be sent on the bus when reconfiguration is in progress. + */ +struct slim_sched { + enum slim_clk_state clk_state; + struct completion pause_comp; + struct mutex m_reconf; +}; + /** * struct slim_controller - Controls every instance of SLIMbus * (similar to 'master' on SPI) @@ -95,6 +141,7 @@ struct slim_msg_txn { * @devices: Slim device list * @tid_idr: tid id allocator * @txn_lock: Lock to protect table of transactions + * @sched: scheduler structure used by the controller * @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. @@ -105,6 +152,9 @@ struct slim_msg_txn { * address table and get_laddr can be used in that case so that controller * can do this assignment. Use case is when the master is on the remote * processor side, who is resposible for allocating laddr. + * @wakeup: This function pointer implements controller-specific procedure + * to wake it up from clock-pause. Framework will call this to bring + * the controller out of clock pause. * * 'Manager device' is responsible for device management, bandwidth * allocation, channel setup, and port associations per channel. @@ -139,12 +189,14 @@ struct slim_controller { struct list_head devices; struct idr tid_idr; spinlock_t txn_lock; + struct slim_sched sched; int (*xfer_msg)(struct slim_controller *ctrl, struct slim_msg_txn *tx); 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); + int (*wakeup)(struct slim_controller *ctrl); };
int slim_device_report_present(struct slim_controller *ctrl, @@ -154,6 +206,7 @@ int slim_register_controller(struct slim_controller *ctrl); int slim_unregister_controller(struct slim_controller *ctrl); void slim_msg_response(struct slim_controller *ctrl, u8 *reply, u8 tid, u8 l); int slim_do_transfer(struct slim_controller *ctrl, struct slim_msg_txn *txn); +int slim_ctrl_clk_pause(struct slim_controller *ctrl, bool wakeup, u8 restart);
static inline bool slim_tid_txn(u8 mt, u8 mc) {