ASoC: fsl_sai: Add pm qos cpu latency support

On SoCs such as i.MX7ULP, cpuidle has some levels which
may disable system/bus clocks, so need to add pm_qos to
prevent cpuidle from entering low level idles and make sure
system/bus clocks are enabled when sai is active.
Signed-off-by: Shengjiu Wang <shengjiu.wang@nxp.com>
Link: https://lore.kernel.org/r/1613983220-5373-1-git-send-email-shengjiu.wang@nxp.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/fsl/fsl_sai.c

@@ -10,6 +10,7 @@
 #include <linux/module.h>
 #include <linux/of_address.h>
 #include <linux/of_device.h>
+#include <linux/pm_qos.h>
 #include <linux/pm_runtime.h>
 #include <linux/regmap.h>
 #include <linux/slab.h>
@@ -1177,6 +1178,7 @@ static const struct fsl_sai_soc_data fsl_sai_vf610_data = {
 	.fifo_depth = 32,
 	.reg_offset = 0,
 	.mclk0_is_mclk1 = false,
+	.flags = 0,
 };
 
 static const struct fsl_sai_soc_data fsl_sai_imx6sx_data = {
@@ -1185,6 +1187,7 @@ static const struct fsl_sai_soc_data fsl_sai_imx6sx_data = {
 	.fifo_depth = 32,
 	.reg_offset = 0,
 	.mclk0_is_mclk1 = true,
+	.flags = 0,
 };
 
 static const struct fsl_sai_soc_data fsl_sai_imx7ulp_data = {
@@ -1193,6 +1196,7 @@ static const struct fsl_sai_soc_data fsl_sai_imx7ulp_data = {
 	.fifo_depth = 16,
 	.reg_offset = 8,
 	.mclk0_is_mclk1 = false,
+	.flags = PMQOS_CPU_LATENCY,
 };
 
 static const struct fsl_sai_soc_data fsl_sai_imx8mq_data = {
@@ -1201,6 +1205,7 @@ static const struct fsl_sai_soc_data fsl_sai_imx8mq_data = {
 	.fifo_depth = 128,
 	.reg_offset = 8,
 	.mclk0_is_mclk1 = false,
+	.flags = 0,
 };
 
 static const struct fsl_sai_soc_data fsl_sai_imx8qm_data = {
@@ -1209,6 +1214,7 @@ static const struct fsl_sai_soc_data fsl_sai_imx8qm_data = {
 	.fifo_depth = 64,
 	.reg_offset = 0,
 	.mclk0_is_mclk1 = false,
+	.flags = 0,
 };
 
 static const struct of_device_id fsl_sai_ids[] = {
@@ -1235,6 +1241,9 @@ static int fsl_sai_runtime_suspend(struct device *dev)
 
 	clk_disable_unprepare(sai->bus_clk);
 
+	if (sai->soc_data->flags & PMQOS_CPU_LATENCY)
+		cpu_latency_qos_remove_request(&sai->pm_qos_req);
+
 	regcache_cache_only(sai->regmap, true);
 
 	return 0;
@@ -1264,6 +1273,9 @@ static int fsl_sai_runtime_resume(struct device *dev)
 			goto disable_tx_clk;
 	}
 
+	if (sai->soc_data->flags & PMQOS_CPU_LATENCY)
+		cpu_latency_qos_add_request(&sai->pm_qos_req, 0);
+
 	regcache_cache_only(sai->regmap, false);
 	regcache_mark_dirty(sai->regmap);
 	regmap_write(sai->regmap, FSL_SAI_TCSR(ofs), FSL_SAI_CSR_SR);

sound/soc/fsl/fsl_sai.h

@@ -216,12 +216,15 @@
 #define FSL_SAI_MAXBURST_TX 6
 #define FSL_SAI_MAXBURST_RX 6
 
+#define PMQOS_CPU_LATENCY   BIT(0)
+
 struct fsl_sai_soc_data {
 	bool use_imx_pcm;
 	bool use_edma;
 	bool mclk0_is_mclk1;
 	unsigned int fifo_depth;
 	unsigned int reg_offset;
+	unsigned int flags;
 };
 
 /**
@@ -273,6 +276,7 @@ struct fsl_sai {
 	struct snd_dmaengine_dai_dma_data dma_params_tx;
 	struct fsl_sai_verid verid;
 	struct fsl_sai_param param;
+	struct pm_qos_request pm_qos_req;
 };
 
 #define TX 1