ASoC: amd: ps: Add a module parameter to influence pdm_gain

In case of regressions for any users that the new pdm_gain value is
too high and for additional debugging, introduce a module parameter
that would let them configure it.

This parameter should be removed in the future:
 * If it's determined that the parameter is not needed, just hardcode
   the correct value as before
 * If users do end up using it to debug and report different values
   we should introduce a config knob that can have policy set by ucm.
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Reviewed-by: Jaroslav Kysela <perex@perex.cz>
Link: https://lore.kernel.org/r/20230131184653.10216-7-mario.limonciello@amd.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/amd/ps/acp63.h

@@ -29,7 +29,7 @@
 #define ACP_ERROR_STAT	29
 #define PDM_DECIMATION_FACTOR	2
 #define ACP_PDM_CLK_FREQ_MASK	7
-#define ACP_WOV_MISC_CTRL_MASK	0x18
+#define ACP_WOV_GAIN_CONTROL	GENMASK(4, 3)
 #define ACP_PDM_ENABLE		1
 #define ACP_PDM_DISABLE		0
 #define ACP_PDM_DMA_EN_STATUS	2

sound/soc/amd/ps/ps-pdm-dma.c

@@ -7,6 +7,7 @@
 
 #include <linux/platform_device.h>
 #include <linux/module.h>
+#include <linux/bitfield.h>
 #include <linux/err.h>
 #include <linux/io.h>
 #include <sound/pcm_params.h>
@@ -18,6 +19,10 @@
 
 #define DRV_NAME "acp_ps_pdm_dma"
 
+static int pdm_gain = 3;
+module_param(pdm_gain, int, 0644);
+MODULE_PARM_DESC(pdm_gain, "Gain control (0-3)");
+
 static const struct snd_pcm_hardware acp63_pdm_hardware_capture = {
 	.info = SNDRV_PCM_INFO_INTERLEAVED |
 		SNDRV_PCM_INFO_BLOCK_TRANSFER |
@@ -55,7 +60,8 @@ static void acp63_enable_pdm_clock(void __iomem *acp_base)
 
 	acp63_writel(pdm_clk_enable, acp_base + ACP_WOV_CLK_CTRL);
 	pdm_ctrl = acp63_readl(acp_base + ACP_WOV_MISC_CTRL);
-	pdm_ctrl |= ACP_WOV_MISC_CTRL_MASK;
+	pdm_ctrl &= ~ACP_WOV_GAIN_CONTROL;
+	pdm_ctrl |= FIELD_PREP(ACP_WOV_GAIN_CONTROL, clamp(pdm_gain, 0, 3));
 	acp63_writel(pdm_ctrl, acp_base + ACP_WOV_MISC_CTRL);
 }