ASoC: fsl_micfil: Add support for PLL switch at runtime

i.MX8MQ/MN/MM/MP platforms typically have 2 AUDIO PLLs being
configured to handle 8kHz and 11kHz series audio rates.

The patch implements the functionality to select at runtime
the appropriate AUDIO PLL as function of audio file rate.

Signed-off-by: Viorel Suman <[e-mail]>
Signed-off-by: Shengjiu Wang <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Mark Brown <[e-mail]>

sound/soc/fsl/Kconfig

···
 	select REGMAP_MMIO
 	select SND_SOC_IMX_PCM_DMA if SND_IMX_SOC != n
 	select SND_SOC_GENERIC_DMAENGINE_PCM
+	select SND_SOC_FSL_UTILS
 	help
 	  Say Y if you want to add Pulse Density Modulation microphone
 	  interface (MICFIL) support for NXP.

sound/soc/fsl/fsl_micfil.c

···
 #include <sound/core.h>
 
 #include "fsl_micfil.h"
+#include "fsl_utils.h"
 
 #define MICFIL_OSR_DEFAULT	16
 
···
 	const struct fsl_micfil_soc_data *soc;
 	struct clk *busclk;
 	struct clk *mclk;
+	struct clk *pll8k_clk;
+	struct clk *pll11k_clk;
 	struct snd_dmaengine_dai_dma_data dma_params_rx;
 	struct sdma_peripheral_config sdmacfg;
 	unsigned int dataline;
···
 	return 0;
 }
 
+static int fsl_micfil_reparent_rootclk(struct fsl_micfil *micfil, unsigned int sample_rate)
+{
+	struct device *dev = &micfil->pdev->dev;
+	u64 ratio = sample_rate;
+	struct clk *clk;
+	int ret;
+
+	/* Get root clock */
+	clk = micfil->mclk;
+
+	/* Disable clock first, for it was enabled by pm_runtime */
+	clk_disable_unprepare(clk);
+	fsl_asoc_reparent_pll_clocks(dev, clk, micfil->pll8k_clk,
+				     micfil->pll11k_clk, ratio);
+	ret = clk_prepare_enable(clk);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
 static int fsl_micfil_hw_params(struct snd_pcm_substream *substream,
 				struct snd_pcm_hw_params *params,
 				struct snd_soc_dai *dai)
···
 	/* enable channels */
 	ret = regmap_update_bits(micfil->regmap, REG_MICFIL_CTRL1,
 				 0xFF, ((1 << channels) - 1));
+	if (ret)
+		return ret;
+
+	ret = fsl_micfil_reparent_rootclk(micfil, rate);
 	if (ret)
 		return ret;
 
···
 			PTR_ERR(micfil->busclk));
 		return PTR_ERR(micfil->busclk);
 	}
+
+	fsl_asoc_get_pll_clocks(&pdev->dev, &micfil->pll8k_clk,
+				&micfil->pll11k_clk);
 
 	/* init regmap */
 	regs = devm_platform_get_and_ioremap_resource(pdev, 0, &res);