ASoC: SOF: imx8m: Use reset controller API to control the DSP

DSP on i.MX8MP doesn't have a direct reset line so according to hardware
design team in order to handle assert/deassert/reset functionality we
need to use a combination of control bits from two modules. Audio block
control module for Run/Stall control of the DSP and DAP module in order
to do software reset.

In a first step, for i.MX8MP we are switching on using the reset
controller API to handle the DSP Run/Stall bits i.MX8MP. This comes with
the advantage of offering a better probe ordering and a more natural way
of abstracting the Audio block control bits.

Reviewed-by: Bard Liao <[e-mail]>
Reviewed-by: Péter Ujfalusi <[e-mail]>
Reviewed-by: Laurentiu Mihalcea <[e-mail]>
Tested-by: Laurentiu Mihalcea <[e-mail]>
Signed-off-by: Daniel Baluta <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Mark Brown <[e-mail]>

sound/soc/sof/imx/imx8.c

···
 #include <linux/arm-smccc.h>
 #include <linux/firmware/imx/svc/misc.h>
 #include <linux/mfd/syscon.h>
+#include <linux/reset.h>
 
 #include "imx-common.h"
 
···
 #define IMX8M_DAP_DEBUG_SIZE (64 * 1024)
 #define IMX8M_DAP_PWRCTL (0x4000 + 0x3020)
 #define IMX8M_PWRCTL_CORERESET BIT(16)
-
-#define AudioDSP_REG0 0x100
-#define AudioDSP_REG1 0x104
-#define AudioDSP_REG2 0x108
-#define AudioDSP_REG3 0x10c
-
-#define AudioDSP_REG2_RUNSTALL  BIT(5)
 
 /* imx8ulp macros */
 #define FSL_SIP_HIFI_XRDC       0xc200000e
···
 struct imx8m_chip_data {
 	void __iomem *dap;
 	struct regmap *regmap;
+	struct reset_control *run_stall;
 };
 
 /*
···
 	/* keep reset asserted for 10 cycles */
 	usleep_range(1, 2);
 
-	regmap_update_bits(chip->regmap, AudioDSP_REG2,
-			   AudioDSP_REG2_RUNSTALL, AudioDSP_REG2_RUNSTALL);
+	reset_control_assert(chip->run_stall);
 
 	/* take the DSP out of reset and keep stalled for FW loading */
 	pwrctl = readl(chip->dap + IMX8M_DAP_PWRCTL);
···
 {
 	struct imx8m_chip_data *chip = get_chip_pdata(sdev);
 
-	regmap_update_bits(chip->regmap, AudioDSP_REG2, AudioDSP_REG2_RUNSTALL, 0);
-
-	return 0;
+	return reset_control_deassert(chip->run_stall);
 }
 
 static int imx8m_probe(struct snd_sof_dev *sdev)
···
 		return dev_err_probe(sdev->dev, -ENODEV,
 				     "failed to ioremap DAP\n");
 
-	chip->regmap = syscon_regmap_lookup_by_phandle(sdev->dev->of_node, "fsl,dsp-ctrl");
-	if (IS_ERR(chip->regmap))
-		return dev_err_probe(sdev->dev, PTR_ERR(chip->regmap),
-				     "failed to fetch dsp ctrl regmap\n");
+	chip->run_stall = devm_reset_control_get_exclusive(sdev->dev, "runstall");
+	if (IS_ERR(chip->run_stall))
+		return dev_err_probe(sdev->dev, PTR_ERR(chip->run_stall),
+				     "failed to get dsp runstall reset control\n");
 
 	common->chip_pdata = chip;