The driver probe takes care of basic initialization and is invoked when a Slave becomes attached, after a match between the Slave DevID registers and ACPI/DT entries.

The update_status callback is invoked when a Slave state changes, e.g. when it is assigned a non-zero Device Number and it reports with an ATTACHED/ALERT state.

The state change detection is usually hardware-based and based on the SoundWire frame rate (e.g. double-digit microseconds) while the probe is a pure software operation, which may involve a kernel module load. In corner cases, it's possible that the state changes before the probe completes.

This patch suggests the use of wait_for_completion to avoid races on startup, so that the update_status callback does not rely on invalid pointers/data structures.

Signed-off-by: Rander Wang rander.wang@intel.com Signed-off-by: Pierre-Louis Bossart pierre-louis.bossart@linux.intel.com --- drivers/soundwire/bus.c | 25 ++++++++++++++++++++++--- drivers/soundwire/bus.h | 1 + drivers/soundwire/bus_type.c | 5 +++++ drivers/soundwire/slave.c | 2 ++ 4 files changed, 30 insertions(+), 3 deletions(-)

diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c index 6106577fb3ed..4980dfd6f3a3 100644 --- a/drivers/soundwire/bus.c +++ b/drivers/soundwire/bus.c @@ -970,10 +970,29 @@ static int sdw_handle_slave_alerts(struct sdw_slave *slave) static int sdw_update_slave_status(struct sdw_slave *slave, enum sdw_slave_status status) { - if (slave->ops && slave->ops->update_status) - return slave->ops->update_status(slave, status); + unsigned long time;

- return 0; + if (!slave->probed) { + /* + * the slave status update is typically handled in an + * interrupt thread, which can race with the driver + * probe, e.g. when a module needs to be loaded. + * + * make sure the probe is complete before updating + * status. + */ + time = wait_for_completion_timeout(&slave->probe_complete, + msecs_to_jiffies(DEFAULT_PROBE_TIMEOUT)); + if (!time) { + dev_err(&slave->dev, "Probe not complete, timed out\n"); + return -ETIMEDOUT; + } + } + + if (!slave->ops || !slave->ops->update_status) + return 0; + + return slave->ops->update_status(slave, status); }

/** diff --git a/drivers/soundwire/bus.h b/drivers/soundwire/bus.h index cb482da914da..acb8d11a4c84 100644 --- a/drivers/soundwire/bus.h +++ b/drivers/soundwire/bus.h @@ -5,6 +5,7 @@ #define __SDW_BUS_H

#define DEFAULT_BANK_SWITCH_TIMEOUT 3000 +#define DEFAULT_PROBE_TIMEOUT 2000

#if IS_ENABLED(CONFIG_ACPI) int sdw_acpi_find_slaves(struct sdw_bus *bus); diff --git a/drivers/soundwire/bus_type.c b/drivers/soundwire/bus_type.c index 4a465f55039f..17f096dd6806 100644 --- a/drivers/soundwire/bus_type.c +++ b/drivers/soundwire/bus_type.c @@ -110,6 +110,11 @@ static int sdw_drv_probe(struct device *dev) slave->bus->clk_stop_timeout = max_t(u32, slave->bus->clk_stop_timeout, slave->prop.clk_stop_timeout);

+ slave->probed = true; + complete(&slave->probe_complete); + + dev_dbg(dev, "probe complete\n"); + return 0; }

diff --git a/drivers/soundwire/slave.c b/drivers/soundwire/slave.c index 19919975bb6d..08db0488e02d 100644 --- a/drivers/soundwire/slave.c +++ b/drivers/soundwire/slave.c @@ -47,6 +47,8 @@ static int sdw_slave_add(struct sdw_bus *bus, slave->bus = bus; slave->status = SDW_SLAVE_UNATTACHED; slave->dev_num = 0; + init_completion(&slave->probe_complete); + slave->probed = false;

mutex_lock(&bus->bus_lock); list_add_tail(&slave->node, &bus->slaves);

Waiting for the enumeration to be complete may not be enough for a Slave driver, there is a possible race condition between resume operations and initializations handled in an interrupt thread, which can results in settings not being fully restored after system or pm_runtime resume.

This patch builds on the changes added for enumeration_complete, init_completion() is called when the Slave device becomes UNATTACHED, as done with enumeration_complete.

The difference with the enumeration_complete case is that complete() is signaled after the Slave device is fully initialized after the .update_status() callback is called.

A Slave device driver can decide to wait on either of the two complete() cases, depending on its initialization code and requirements.

Signed-off-by: Rander Wang rander.wang@linux.intel.com Signed-off-by: Pierre-Louis Bossart pierre-louis.bossart@linux.intel.com --- drivers/soundwire/bus.c | 8 ++++++++ drivers/soundwire/slave.c | 1 + 2 files changed, 9 insertions(+)

diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c index a2267c3a1d2d..ea04cf5f5bdc 100644 --- a/drivers/soundwire/bus.c +++ b/drivers/soundwire/bus.c @@ -621,6 +621,7 @@ static void sdw_modify_slave_status(struct sdw_slave *slave, __func__, slave->dev_num);

init_completion(&slave->enumeration_complete); + init_completion(&slave->initialization_complete);

} else if ((status == SDW_SLAVE_ATTACHED) && (slave->status == SDW_SLAVE_UNATTACHED)) { @@ -1025,6 +1026,7 @@ int sdw_handle_slave_status(struct sdw_bus *bus, { enum sdw_slave_status prev_status; struct sdw_slave *slave; + bool attached_initializing; int i, ret = 0;

/* first check if any Slaves fell off the bus */ @@ -1070,6 +1072,8 @@ int sdw_handle_slave_status(struct sdw_bus *bus, if (!slave) continue;

+ attached_initializing = false; + switch (status[i]) { case SDW_SLAVE_UNATTACHED: if (slave->status == SDW_SLAVE_UNATTACHED) @@ -1096,6 +1100,8 @@ int sdw_handle_slave_status(struct sdw_bus *bus, if (prev_status == SDW_SLAVE_ALERT) break;

+ attached_initializing = true; + ret = sdw_initialize_slave(slave); if (ret) dev_err(bus->dev, @@ -1114,6 +1120,8 @@ int sdw_handle_slave_status(struct sdw_bus *bus, if (ret) dev_err(slave->bus->dev, "Update Slave status failed:%d\n", ret); + if (attached_initializing) + complete(&slave->initialization_complete); }

return ret; diff --git a/drivers/soundwire/slave.c b/drivers/soundwire/slave.c index e767a78066ee..aace57fae7f8 100644 --- a/drivers/soundwire/slave.c +++ b/drivers/soundwire/slave.c @@ -47,6 +47,7 @@ static int sdw_slave_add(struct sdw_bus *bus, slave->bus = bus; slave->status = SDW_SLAVE_UNATTACHED; init_completion(&slave->enumeration_complete); + init_completion(&slave->initialization_complete); slave->dev_num = 0; init_completion(&slave->probe_complete); slave->probed = false;

While handling the Device0, we can safely use sdw_write_no_pm.

This move will also helps us track that all other usages of sdw_write() happen when the Slave is already enumerated.

Signed-off-by: Pierre-Louis Bossart pierre-louis.bossart@linux.intel.com --- drivers/soundwire/bus.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c index c525b9b50453..dfe27e3ca815 100644 --- a/drivers/soundwire/bus.c +++ b/drivers/soundwire/bus.c @@ -522,7 +522,7 @@ static int sdw_assign_device_num(struct sdw_slave *slave) dev_num = slave->dev_num; slave->dev_num = 0;

- ret = sdw_write(slave, SDW_SCP_DEVNUMBER, dev_num); + ret = sdw_write_no_pm(slave, SDW_SCP_DEVNUMBER, dev_num); if (ret < 0) { dev_err(&slave->dev, "Program device_num %d failed: %d\n", dev_num, ret);

Before removing the slave device, disable pm_runtime to prevent any race condition with the resume being executed after the bus and slave devices are removed.

Since this pm_runtime_disable() is handled in common routines, implementations of Slave drivers do not need to call it in their .remove() routine.

Signed-off-by: Pierre-Louis Bossart pierre-louis.bossart@linux.intel.com --- drivers/soundwire/bus.c | 2 ++ 1 file changed, 2 insertions(+)

diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c index 57dec61142e5..33bb273454cf 100644 --- a/drivers/soundwire/bus.c +++ b/drivers/soundwire/bus.c @@ -113,6 +113,8 @@ static int sdw_delete_slave(struct device *dev, void *data) struct sdw_slave *slave = dev_to_sdw_dev(dev); struct sdw_bus *bus = slave->bus;

+ pm_runtime_disable(dev); + sdw_slave_debugfs_exit(slave);

mutex_lock(&bus->bus_lock);

From: Rander Wang rander.wang@intel.com

SoundWire supports two clock stop modes. Add support to handle the clock stop modes and add pm_runtime calls in the bus.

Credits: this patch is based on an earlier internal contribution by Vinod Koul, Sanyog Kale, Shreyas Nc and Hardik Shah.

Signed-off-by: Bard Liao yung-chuan.liao@linux.intel.com Signed-off-by: Rander Wang rander.wang@intel.com Signed-off-by: Pierre-Louis Bossart pierre-louis.bossart@linux.intel.com --- drivers/soundwire/bus.c | 332 ++++++++++++++++++++++++++++++++++ include/linux/soundwire/sdw.h | 24 +++ 2 files changed, 356 insertions(+)

diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c index 23bc24c8e9d1..3395abd2ed39 100644 --- a/drivers/soundwire/bus.c +++ b/drivers/soundwire/bus.c @@ -2,6 +2,7 @@ // Copyright(c) 2015-17 Intel Corporation.

#include <linux/acpi.h> +#include <linux/delay.h> #include <linux/mod_devicetable.h> #include <linux/pm_runtime.h> #include <linux/soundwire/sdw_registers.h> @@ -359,6 +360,52 @@ static int sdw_write_no_pm(struct sdw_slave *slave, u32 addr, u8 value) return sdw_nwrite_no_pm(slave, addr, 1, &value); }

+static int +sdw_bread_no_pm(struct sdw_bus *bus, u16 dev_num, u32 addr) +{ + struct sdw_msg msg; + u8 buf; + int ret; + + ret = sdw_fill_msg(&msg, NULL, addr, 1, dev_num, + SDW_MSG_FLAG_READ, &buf); + if (ret) + return ret; + + ret = sdw_transfer(bus, &msg); + if (ret < 0) + return ret; + else + return buf; +} + +static int +sdw_bwrite_no_pm(struct sdw_bus *bus, u16 dev_num, u32 addr, u8 value) +{ + struct sdw_msg msg; + int ret; + + ret = sdw_fill_msg(&msg, NULL, addr, 1, dev_num, + SDW_MSG_FLAG_WRITE, &value); + if (ret) + return ret; + + return sdw_transfer(bus, &msg); +} + +static int +sdw_read_no_pm(struct sdw_slave *slave, u32 addr) +{ + u8 buf; + int ret; + + ret = sdw_nread_no_pm(slave, addr, 1, &buf); + if (ret < 0) + return ret; + else + return buf; +} + /** * sdw_nread() - Read "n" contiguous SDW Slave registers * @slave: SDW Slave @@ -673,6 +720,291 @@ static void sdw_modify_slave_status(struct sdw_slave *slave, mutex_unlock(&slave->bus->bus_lock); }

+static enum sdw_clk_stop_mode sdw_get_clk_stop_mode(struct sdw_slave *slave) +{ + enum sdw_clk_stop_mode mode; + + /* + * Query for clock stop mode if Slave implements + * ops->get_clk_stop_mode, else read from property. + */ + if (slave->ops && slave->ops->get_clk_stop_mode) { + mode = slave->ops->get_clk_stop_mode(slave); + } else { + if (slave->prop.clk_stop_mode1) + mode = SDW_CLK_STOP_MODE1; + else + mode = SDW_CLK_STOP_MODE0; + } + + return mode; +} + +static int sdw_slave_clk_stop_callback(struct sdw_slave *slave, + enum sdw_clk_stop_mode mode, + enum sdw_clk_stop_type type) +{ + int ret; + + if (slave->ops && slave->ops->clk_stop) { + ret = slave->ops->clk_stop(slave, mode, type); + if (ret < 0) { + dev_err(&slave->dev, + "Clk Stop type =%d failed: %d\n", type, ret); + return ret; + } + } + + return 0; +} + +static int sdw_slave_clk_stop_prepare(struct sdw_slave *slave, + enum sdw_clk_stop_mode mode, + bool prepare) +{ + bool wake_en; + u32 val = 0; + int ret; + + wake_en = slave->prop.wake_capable; + + if (prepare) { + val = SDW_SCP_SYSTEMCTRL_CLK_STP_PREP; + + if (mode == SDW_CLK_STOP_MODE1) + val |= SDW_SCP_SYSTEMCTRL_CLK_STP_MODE1; + + if (wake_en) + val |= SDW_SCP_SYSTEMCTRL_WAKE_UP_EN; + } else { + val = sdw_read_no_pm(slave, SDW_SCP_SYSTEMCTRL); + + val &= ~(SDW_SCP_SYSTEMCTRL_CLK_STP_PREP); + } + + ret = sdw_write_no_pm(slave, SDW_SCP_SYSTEMCTRL, val); + + if (ret != 0) + dev_err(&slave->dev, + "Clock Stop prepare failed for slave: %d", ret); + + return ret; +} + +static int sdw_bus_wait_for_clk_prep_deprep(struct sdw_bus *bus, u16 dev_num) +{ + int retry = bus->clk_stop_timeout; + int val; + + do { + val = sdw_bread_no_pm(bus, dev_num, SDW_SCP_STAT) & + SDW_SCP_STAT_CLK_STP_NF; + if (!val) { + dev_info(bus->dev, "clock stop prep/de-prep done slave:%d", + dev_num); + return 0; + } + + usleep_range(1000, 1500); + retry--; + } while (retry); + + dev_err(bus->dev, "clock stop prep/de-prep failed slave:%d", + dev_num); + + return -ETIMEDOUT; +} + +/** + * sdw_bus_prep_clk_stop: prepare Slave(s) for clock stop + * + * @bus: SDW bus instance + * + * Query Slave for clock stop mode and prepare for that mode. + */ +int sdw_bus_prep_clk_stop(struct sdw_bus *bus) +{ + enum sdw_clk_stop_mode slave_mode; + bool simple_clk_stop = true; + struct sdw_slave *slave; + bool is_slave = false; + int ret = 0; + + /* + * In order to save on transition time, prepare + * each Slave and then wait for all Slave(s) to be + * prepared for clock stop. + */ + list_for_each_entry(slave, &bus->slaves, node) { + if (!slave->dev_num) + continue; + + /* Identify if Slave(s) are available on Bus */ + is_slave = true; + + if (slave->status != SDW_SLAVE_ATTACHED && + slave->status != SDW_SLAVE_ALERT) + continue; + + slave_mode = sdw_get_clk_stop_mode(slave); + slave->curr_clk_stop_mode = slave_mode; + + ret = sdw_slave_clk_stop_callback(slave, slave_mode, + SDW_CLK_PRE_PREPARE); + if (ret < 0) { + dev_err(&slave->dev, + "pre-prepare failed:%d", ret); + return ret; + } + + ret = sdw_slave_clk_stop_prepare(slave, + slave_mode, true); + if (ret < 0) { + dev_err(&slave->dev, + "pre-prepare failed:%d", ret); + return ret; + } + + if (slave_mode == SDW_CLK_STOP_MODE1) + simple_clk_stop = false; + } + + if (is_slave && !simple_clk_stop) { + ret = sdw_bus_wait_for_clk_prep_deprep(bus, + SDW_BROADCAST_DEV_NUM); + if (ret < 0) + return ret; + } + + /* Inform slaves that prep is done */ + list_for_each_entry(slave, &bus->slaves, node) { + if (!slave->dev_num) + continue; + + if (slave->status != SDW_SLAVE_ATTACHED && + slave->status != SDW_SLAVE_ALERT) + continue; + + slave_mode = slave->curr_clk_stop_mode; + + if (slave_mode == SDW_CLK_STOP_MODE1) { + ret = sdw_slave_clk_stop_callback(slave, + slave_mode, + SDW_CLK_POST_PREPARE); + + if (ret < 0) { + dev_err(&slave->dev, + "post-prepare failed:%d", ret); + } + } + } + + return ret; +} +EXPORT_SYMBOL(sdw_bus_prep_clk_stop); + +/** + * sdw_bus_clk_stop: stop bus clock + * + * @bus: SDW bus instance + * + * After preparing the Slaves for clock stop, stop the clock by broadcasting + * write to SCP_CTRL register. + */ +int sdw_bus_clk_stop(struct sdw_bus *bus) +{ + int ret; + + /* + * broadcast clock stop now, attached Slaves will ACK this, + * unattached will ignore + */ + ret = sdw_bwrite_no_pm(bus, SDW_BROADCAST_DEV_NUM, + SDW_SCP_CTRL, SDW_SCP_CTRL_CLK_STP_NOW); + if (ret < 0) { + dev_err(bus->dev, + "ClockStopNow Broadcast message failed %d", ret); + return ret; + } + + return 0; +} +EXPORT_SYMBOL(sdw_bus_clk_stop); + +/** + * sdw_bus_exit_clk_stop: Exit clock stop mode + * + * @bus: SDW bus instance + * + * This De-prepares the Slaves by exiting Clock Stop Mode 0. For the Slaves + * exiting Clock Stop Mode 1, they will be de-prepared after they enumerate + * back. + */ +int sdw_bus_exit_clk_stop(struct sdw_bus *bus) +{ + enum sdw_clk_stop_mode mode; + bool simple_clk_stop = true; + struct sdw_slave *slave; + bool is_slave = false; + int ret; + + /* + * In order to save on transition time, de-prepare + * each Slave and then wait for all Slave(s) to be + * de-prepared after clock resume. + */ + list_for_each_entry(slave, &bus->slaves, node) { + if (!slave->dev_num) + continue; + + /* Identify if Slave(s) are available on Bus */ + is_slave = true; + + if (slave->status != SDW_SLAVE_ATTACHED && + slave->status != SDW_SLAVE_ALERT) + continue; + + mode = slave->curr_clk_stop_mode; + + if (mode == SDW_CLK_STOP_MODE1) { + simple_clk_stop = false; + continue; + } + + ret = sdw_slave_clk_stop_callback(slave, mode, + SDW_CLK_PRE_DEPREPARE); + if (ret < 0) + dev_warn(&slave->dev, + "clk stop deprep failed:%d", ret); + + ret = sdw_slave_clk_stop_prepare(slave, mode, + false); + + if (ret < 0) + dev_warn(&slave->dev, + "clk stop deprep failed:%d", ret); + } + + if (is_slave && !simple_clk_stop) + sdw_bus_wait_for_clk_prep_deprep(bus, SDW_BROADCAST_DEV_NUM); + + list_for_each_entry(slave, &bus->slaves, node) { + if (!slave->dev_num) + continue; + + if (slave->status != SDW_SLAVE_ATTACHED && + slave->status != SDW_SLAVE_ALERT) + continue; + + mode = slave->curr_clk_stop_mode; + sdw_slave_clk_stop_callback(slave, mode, + SDW_CLK_POST_DEPREPARE); + } + + return 0; +} +EXPORT_SYMBOL(sdw_bus_exit_clk_stop); + int sdw_configure_dpn_intr(struct sdw_slave *slave, int port, bool enable, int mask) { diff --git a/include/linux/soundwire/sdw.h b/include/linux/soundwire/sdw.h index b451bb622335..b8427df034ce 100644 --- a/include/linux/soundwire/sdw.h +++ b/include/linux/soundwire/sdw.h @@ -79,6 +79,21 @@ enum sdw_slave_status { SDW_SLAVE_RESERVED = 3, };

+/** + * enum sdw_clk_stop_type: clock stop operations + * + * @SDW_CLK_PRE_PREPARE: pre clock stop prepare + * @SDW_CLK_POST_PREPARE: post clock stop prepare + * @SDW_CLK_PRE_DEPREPARE: pre clock stop de-prepare + * @SDW_CLK_POST_DEPREPARE: post clock stop de-prepare + */ +enum sdw_clk_stop_type { + SDW_CLK_PRE_PREPARE = 0, + SDW_CLK_POST_PREPARE, + SDW_CLK_PRE_DEPREPARE, + SDW_CLK_POST_DEPREPARE, +}; + /** * enum sdw_command_response - Command response as defined by SDW spec * @SDW_CMD_OK: cmd was successful @@ -533,6 +548,11 @@ struct sdw_slave_ops { int (*port_prep)(struct sdw_slave *slave, struct sdw_prepare_ch *prepare_ch, enum sdw_port_prep_ops pre_ops); + int (*get_clk_stop_mode)(struct sdw_slave *slave); + int (*clk_stop)(struct sdw_slave *slave, + enum sdw_clk_stop_mode mode, + enum sdw_clk_stop_type type); + };

/** @@ -575,6 +595,7 @@ struct sdw_slave { #endif struct list_head node; struct completion *port_ready; + enum sdw_clk_stop_mode curr_clk_stop_mode; u16 dev_num; u16 dev_num_sticky; bool probed; @@ -892,6 +913,9 @@ int sdw_prepare_stream(struct sdw_stream_runtime *stream); int sdw_enable_stream(struct sdw_stream_runtime *stream); int sdw_disable_stream(struct sdw_stream_runtime *stream); int sdw_deprepare_stream(struct sdw_stream_runtime *stream); +int sdw_bus_prep_clk_stop(struct sdw_bus *bus); +int sdw_bus_clk_stop(struct sdw_bus *bus); +int sdw_bus_exit_clk_stop(struct sdw_bus *bus);

/* messaging and data APIs */