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Subject[PATCH 09/10] soundwire: bus: add clock stop helpers
Date
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 */

--
2.20.1
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