soundwire: qcom: add runtime pm support

Add support to runtime PM using SoundWire clock stop Mode0 on supported
controller instances and soft reset on instances that do not support
clock stop.

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20220228172528.3489-2-srinivas.kandagatla@linaro.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>

drivers/soundwire/qcom.c

@@ -11,6 +11,7 @@
 #include <linux/of.h>
 #include <linux/of_irq.h>
 #include <linux/of_device.h>
+#include <linux/pm_runtime.h>
 #include <linux/regmap.h>
 #include <linux/slab.h>
 #include <linux/slimbus.h>
@@ -20,6 +21,9 @@
 #include <sound/soc.h>
 #include "bus.h"
 
+#define SWRM_COMP_SW_RESET					0x008
+#define SWRM_COMP_STATUS					0x014
+#define SWRM_FRM_GEN_ENABLED					BIT(0)
 #define SWRM_COMP_HW_VERSION					0x00
 #define SWRM_COMP_CFG_ADDR					0x04
 #define SWRM_COMP_CFG_IRQ_LEVEL_OR_PULSE_MSK			BIT(1)
@@ -29,6 +33,7 @@
 #define SWRM_COMP_PARAMS_RD_FIFO_DEPTH				GENMASK(19, 15)
 #define SWRM_COMP_PARAMS_DOUT_PORTS_MASK			GENMASK(4, 0)
 #define SWRM_COMP_PARAMS_DIN_PORTS_MASK				GENMASK(9, 5)
+#define SWRM_COMP_MASTER_ID					0x104
 #define SWRM_INTERRUPT_STATUS					0x200
 #define SWRM_INTERRUPT_STATUS_RMSK				GENMASK(16, 0)
 #define SWRM_INTERRUPT_STATUS_SLAVE_PEND_IRQ			BIT(0)
@@ -111,6 +116,13 @@
 #define SWR_MAX_CMD_ID	14
 #define MAX_FIFO_RD_RETRY 3
 #define SWR_OVERFLOW_RETRY_COUNT 30
+#define SWRM_LINK_STATUS_RETRY_CNT 100
+
+enum {
+	MASTER_ID_WSA = 1,
+	MASTER_ID_RX,
+	MASTER_ID_TX
+};
 
 struct qcom_swrm_port_config {
 	u8 si;
@@ -159,6 +171,7 @@ struct qcom_swrm_ctrl {
 	u32 slave_status;
 	u32 wr_fifo_depth;
 	u32 rd_fifo_depth;
+	bool clock_stop_not_supported;
 };
 
 struct qcom_swrm_data {
@@ -497,6 +510,7 @@ static irqreturn_t qcom_swrm_irq_handler(int irq, void *dev_id)
 	u32 i;
 	int devnum;
 	int ret = IRQ_HANDLED;
+	clk_prepare_enable(swrm->hclk);
 
 	swrm->reg_read(swrm, SWRM_INTERRUPT_STATUS, &intr_sts);
 	intr_sts_masked = intr_sts & swrm->intr_mask;
@@ -604,6 +618,7 @@ static irqreturn_t qcom_swrm_irq_handler(int irq, void *dev_id)
 		intr_sts_masked = intr_sts & swrm->intr_mask;
 	} while (intr_sts_masked);
 
+	clk_disable_unprepare(swrm->hclk);
 	return ret;
 }
 
@@ -1017,6 +1032,15 @@ static int qcom_swrm_startup(struct snd_pcm_substream *substream,
 	struct snd_soc_dai *codec_dai;
 	int ret, i;
 
+	ret = pm_runtime_get_sync(ctrl->dev);
+	if (ret < 0 && ret != -EACCES) {
+		dev_err_ratelimited(ctrl->dev,
+				    "pm_runtime_get_sync failed in %s, ret %d\n",
+				    __func__, ret);
+		pm_runtime_put_noidle(ctrl->dev);
+		return ret;
+	}
+
 	sruntime = sdw_alloc_stream(dai->name);
 	if (!sruntime)
 		return -ENOMEM;
@@ -1044,6 +1068,9 @@ static void qcom_swrm_shutdown(struct snd_pcm_substream *substream,
 
 	sdw_release_stream(ctrl->sruntime[dai->id]);
 	ctrl->sruntime[dai->id] = NULL;
+	pm_runtime_mark_last_busy(ctrl->dev);
+	pm_runtime_put_autosuspend(ctrl->dev);
+
 }
 
 static const struct snd_soc_dai_ops qcom_swrm_pdm_dai_ops = {
@@ -1197,12 +1224,23 @@ static int qcom_swrm_get_port_config(struct qcom_swrm_ctrl *ctrl)
 static int swrm_reg_show(struct seq_file *s_file, void *data)
 {
 	struct qcom_swrm_ctrl *swrm = s_file->private;
-	int reg, reg_val;
+	int reg, reg_val, ret;
+
+	ret = pm_runtime_get_sync(swrm->dev);
+	if (ret < 0 && ret != -EACCES) {
+		dev_err_ratelimited(swrm->dev,
+				    "pm_runtime_get_sync failed in %s, ret %d\n",
+				    __func__, ret);
+		pm_runtime_put_noidle(swrm->dev);
+	}
 
 	for (reg = 0; reg <= SWR_MSTR_MAX_REG_ADDR; reg += 4) {
 		swrm->reg_read(swrm, reg, &reg_val);
 		seq_printf(s_file, "0x%.3x: 0x%.2x\n", reg, reg_val);
 	}
+	pm_runtime_mark_last_busy(swrm->dev);
+	pm_runtime_put_autosuspend(swrm->dev);
+
 
 	return 0;
 }
@@ -1267,6 +1305,7 @@ static int qcom_swrm_probe(struct platform_device *pdev)
 	ctrl->bus.ops = &qcom_swrm_ops;
 	ctrl->bus.port_ops = &qcom_swrm_port_ops;
 	ctrl->bus.compute_params = &qcom_swrm_compute_params;
+	ctrl->bus.clk_stop_timeout = 300;
 
 	ret = qcom_swrm_get_port_config(ctrl);
 	if (ret)
@@ -1319,6 +1358,21 @@ static int qcom_swrm_probe(struct platform_device *pdev)
 		 (ctrl->version >> 24) & 0xff, (ctrl->version >> 16) & 0xff,
 		 ctrl->version & 0xffff);
 
+	pm_runtime_set_autosuspend_delay(dev, 3000);
+	pm_runtime_use_autosuspend(dev);
+	pm_runtime_mark_last_busy(dev);
+	pm_runtime_set_active(dev);
+	pm_runtime_enable(dev);
+
+	/* Clk stop is not supported on WSA Soundwire masters */
+	if (ctrl->version <= 0x01030000) {
+		ctrl->clock_stop_not_supported = true;
+	} else {
+		ctrl->reg_read(ctrl, SWRM_COMP_MASTER_ID, &val);
+		if (val == MASTER_ID_WSA)
+			ctrl->clock_stop_not_supported = true;
+	}
+
 #ifdef CONFIG_DEBUG_FS
 	ctrl->debugfs = debugfs_create_dir("qualcomm-sdw", ctrl->bus.debugfs);
 	debugfs_create_file("qualcomm-registers", 0400, ctrl->debugfs, ctrl,
@@ -1345,6 +1399,105 @@ static int qcom_swrm_remove(struct platform_device *pdev)
 	return 0;
 }
 
+static bool swrm_wait_for_frame_gen_enabled(struct qcom_swrm_ctrl *swrm)
+{
+	int retry = SWRM_LINK_STATUS_RETRY_CNT;
+	int comp_sts;
+
+	do {
+		swrm->reg_read(swrm, SWRM_COMP_STATUS, &comp_sts);
+
+		if (comp_sts & SWRM_FRM_GEN_ENABLED)
+			return true;
+
+		usleep_range(500, 510);
+	} while (retry--);
+
+	dev_err(swrm->dev, "%s: link status not %s\n", __func__,
+		comp_sts && SWRM_FRM_GEN_ENABLED ? "connected" : "disconnected");
+
+	return false;
+}
+
+static int swrm_runtime_resume(struct device *dev)
+{
+	struct qcom_swrm_ctrl *ctrl = dev_get_drvdata(dev);
+	int ret;
+
+	clk_prepare_enable(ctrl->hclk);
+
+	if (ctrl->clock_stop_not_supported) {
+		reinit_completion(&ctrl->enumeration);
+		ctrl->reg_write(ctrl, SWRM_COMP_SW_RESET, 0x01);
+		usleep_range(100, 105);
+
+		qcom_swrm_init(ctrl);
+
+		usleep_range(100, 105);
+		if (!swrm_wait_for_frame_gen_enabled(ctrl))
+			dev_err(ctrl->dev, "link failed to connect\n");
+
+		/* wait for hw enumeration to complete */
+		wait_for_completion_timeout(&ctrl->enumeration,
+					    msecs_to_jiffies(TIMEOUT_MS));
+		qcom_swrm_get_device_status(ctrl);
+		sdw_handle_slave_status(&ctrl->bus, ctrl->status);
+	} else {
+		ctrl->reg_write(ctrl, SWRM_MCP_BUS_CTRL, SWRM_MCP_BUS_CLK_START);
+		ctrl->reg_write(ctrl, SWRM_INTERRUPT_CLEAR,
+			SWRM_INTERRUPT_STATUS_MASTER_CLASH_DET);
+
+		ctrl->intr_mask |= SWRM_INTERRUPT_STATUS_MASTER_CLASH_DET;
+		ctrl->reg_write(ctrl, SWRM_INTERRUPT_MASK_ADDR, ctrl->intr_mask);
+		ctrl->reg_write(ctrl, SWRM_INTERRUPT_CPU_EN, ctrl->intr_mask);
+
+		usleep_range(100, 105);
+		if (!swrm_wait_for_frame_gen_enabled(ctrl))
+			dev_err(ctrl->dev, "link failed to connect\n");
+
+		ret = sdw_bus_exit_clk_stop(&ctrl->bus);
+		if (ret < 0)
+			dev_err(ctrl->dev, "bus failed to exit clock stop %d\n", ret);
+	}
+
+	return 0;
+}
+
+static int __maybe_unused swrm_runtime_suspend(struct device *dev)
+{
+	struct qcom_swrm_ctrl *ctrl = dev_get_drvdata(dev);
+	int ret;
+
+	if (!ctrl->clock_stop_not_supported) {
+		/* Mask bus clash interrupt */
+		ctrl->intr_mask &= ~SWRM_INTERRUPT_STATUS_MASTER_CLASH_DET;
+		ctrl->reg_write(ctrl, SWRM_INTERRUPT_MASK_ADDR, ctrl->intr_mask);
+		ctrl->reg_write(ctrl, SWRM_INTERRUPT_CPU_EN, ctrl->intr_mask);
+		/* Prepare slaves for clock stop */
+		ret = sdw_bus_prep_clk_stop(&ctrl->bus);
+		if (ret < 0 && ret != -ENODATA) {
+			dev_err(dev, "prepare clock stop failed %d", ret);
+			return ret;
+		}
+
+		ret = sdw_bus_clk_stop(&ctrl->bus);
+		if (ret < 0 && ret != -ENODATA) {
+			dev_err(dev, "bus clock stop failed %d", ret);
+			return ret;
+		}
+	}
+
+	clk_disable_unprepare(ctrl->hclk);
+
+	usleep_range(300, 305);
+
+	return 0;
+}
+
+static const struct dev_pm_ops swrm_dev_pm_ops = {
+	SET_RUNTIME_PM_OPS(swrm_runtime_suspend, swrm_runtime_resume, NULL)
+};
+
 static const struct of_device_id qcom_swrm_of_match[] = {
 	{ .compatible = "qcom,soundwire-v1.3.0", .data = &swrm_v1_3_data },
 	{ .compatible = "qcom,soundwire-v1.5.1", .data = &swrm_v1_5_data },
@@ -1359,6 +1512,7 @@ static struct platform_driver qcom_swrm_driver = {
 	.driver = {
 		.name	= "qcom-soundwire",
 		.of_match_table = qcom_swrm_of_match,
+		.pm = &swrm_dev_pm_ops,
 	}
 };
 module_platform_driver(qcom_swrm_driver);