MLK-18682-2: ASoC: fsl: sai: allow dynamic pll switching

Currently SAI master clock derives from an audio pll that cannot be
changed at runtime. iMX8 SoC has 2 audio plls usually configured to support
either 8000Hz (8k,16k,32k,48k,etc) or 11025Hz (11k,22k,44.1k,88.2k,etc)
ranges of rates - thus at runtime a SAI interface is able to play only one
range of rates. The patch allows dynamic SAI master clock reparenting to
the appropriate audio pll as function of the audio stream rate to be
played/recorded.

Signed-off-by: Viorel Suman <viorel.suman@nxp.com>

2 files changed, 57 insertions, 5 deletions

diff --git a/sound/soc/fsl/fsl_sai.c b/sound/soc/fsl/fsl_sai.c
index 3f7852d2a93a..00a14944aef8 100644
--- a/sound/soc/fsl/fsl_sai.c
+++ b/sound/soc/fsl/fsl_sai.c
@@ -5,6 +5,7 @@
 // Copyright 2012-2016 Freescale Semiconductor, Inc.
 
 #include <linux/clk.h>
+#include <linux/clk-provider.h>
 #include <linux/delay.h>
 #include <linux/dmaengine.h>
 #include <linux/module.h>
@@ -234,6 +235,50 @@ static int fsl_sai_set_dai_sysclk_tr(struct snd_soc_dai *cpu_dai,
 	return 0;
 }
 
+static int fsl_sai_set_mclk_rate(struct snd_soc_dai *dai, int clk_id,
+		unsigned int freq)
+{
+	struct fsl_sai *sai = snd_soc_dai_get_drvdata(dai);
+	struct clk *p = sai->mclk_clk[clk_id], *pll = 0, *npll = 0;
+	u64 ratio = freq;
+	int ret;
+
+	while (p && sai->pll8k_clk && sai->pll11k_clk) {
+		struct clk *pp = clk_get_parent(p);
+
+		if (clk_is_match(pp, sai->pll8k_clk) ||
+		    clk_is_match(pp, sai->pll11k_clk)) {
+			pll = pp;
+			break;
+		}
+		p = pp;
+	}
+
+	if (pll) {
+		npll = (do_div(ratio, 8000) ? sai->pll11k_clk : sai->pll8k_clk);
+		if (!clk_is_match(pll, npll)) {
+			if (sai->mclk_streams == 0) {
+				ret = clk_set_parent(p, npll);
+				if (ret < 0)
+					dev_warn(dai->dev,
+						"failed to set parent %s: %d\n",
+						__clk_get_name(npll), ret);
+			} else {
+				dev_err(dai->dev,
+					"PLL %s is in use by a running stream.\n",
+					__clk_get_name(pll));
+				return -EINVAL;
+			}
+		}
+	}
+
+	ret = clk_set_rate(sai->mclk_clk[clk_id], freq);
+	if (ret < 0)
+		dev_err(dai->dev, "failed to set clock rate (%u): %d\n",
+				freq, ret);
+	return ret;
+}
+
 static int fsl_sai_set_dai_bclk_ratio(struct snd_soc_dai *dai, unsigned int ratio)
 {
 	struct fsl_sai *sai = snd_soc_dai_get_drvdata(dai);
@@ -262,12 +307,9 @@ static int fsl_sai_set_dai_sysclk(struct snd_soc_dai *cpu_dai,
 			return -EINVAL;
 		}
 
-		ret = clk_set_rate(sai->mclk_clk[clk_id], freq);
-		if (ret < 0) {
-			dev_err(cpu_dai->dev, "failed to set clock rate (%u): %d\n",
-					freq, ret);
+		ret = fsl_sai_set_mclk_rate(cpu_dai, clk_id, freq);
+		if (ret < 0)
 			return ret;
-		}
 	}
 
 	ret = fsl_sai_set_dai_sysclk_tr(cpu_dai, clk_id, freq,
@@ -1288,6 +1330,14 @@ static int fsl_sai_probe(struct platform_device *pdev)
 		}
 	}
 
+	sai->pll8k_clk = devm_clk_get(&pdev->dev, "pll8k");
+	if (IS_ERR(sai->pll8k_clk))
+		sai->pll8k_clk = NULL;
+
+	sai->pll11k_clk = devm_clk_get(&pdev->dev, "pll11k");
+	if (IS_ERR(sai->pll11k_clk))
+		sai->pll11k_clk = NULL;
+
 	if (of_find_property(np, "fsl,sai-multi-lane", NULL))
 		sai->is_multi_lane = true;
 
diff --git a/sound/soc/fsl/fsl_sai.h b/sound/soc/fsl/fsl_sai.h
index cb575a2a2501..4627d79dcb4d 100644
--- a/sound/soc/fsl/fsl_sai.h
+++ b/sound/soc/fsl/fsl_sai.h
@@ -239,6 +239,8 @@ struct fsl_sai {
 	struct regmap *regmap;
 	struct clk *bus_clk;
 	struct clk *mclk_clk[FSL_SAI_MCLK_MAX];
+	struct clk *pll8k_clk;
+	struct clk *pll11k_clk;
 
 	bool slave_mode[2];
 	bool is_lsb_first;