reset: imx8mp-audiomix: Switch to using regmap API

Switch to using the regmap API to allow performing register operations
under the same lock. This is needed for cases such as i.MX8ULP's SIM LPAV
where clock gating, reset control and MUX-ing is performed via the same
register (i.e. SYSCTRL0) and different subsystem APIs.

Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Laurentiu Mihalcea <laurentiu.mihalcea@nxp.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

Author: LaurentiuM1234

drivers/reset/reset-imx8mp-audiomix.c

@@ -12,6 +12,7 @@
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/of_address.h>
+#include <linux/regmap.h>
 #include <linux/reset-controller.h>
 
 #define IMX8MP_AUDIOMIX_EARC_RESET_OFFSET	0x200
@@ -43,8 +44,7 @@ static const struct imx8mp_reset_map reset_map[] = {
 
 struct imx8mp_audiomix_reset {
 	struct reset_controller_dev rcdev;
-	spinlock_t lock; /* protect register read-modify-write cycle */
-	void __iomem *base;
+	struct regmap *regmap;
 };
 
 static struct imx8mp_audiomix_reset *to_imx8mp_audiomix_reset(struct reset_controller_dev *rcdev)
@@ -56,26 +56,14 @@ static int imx8mp_audiomix_update(struct reset_controller_dev *rcdev,
 				  unsigned long id, bool assert)
 {
 	struct imx8mp_audiomix_reset *priv = to_imx8mp_audiomix_reset(rcdev);
-	void __iomem *reg_addr = priv->base;
-	unsigned int mask, offset, active_low;
-	unsigned long reg, flags;
+	unsigned int mask, offset, active_low, val;
 
 	mask = reset_map[id].mask;
 	offset = reset_map[id].offset;
 	active_low = reset_map[id].active_low;
+	val = (active_low ^ assert) ? mask : ~mask;
 
-	spin_lock_irqsave(&priv->lock, flags);
-
-	reg = readl(reg_addr + offset);
-	if (active_low ^ assert)
-		reg |= mask;
-	else
-		reg &= ~mask;
-	writel(reg, reg_addr + offset);
-
-	spin_unlock_irqrestore(&priv->lock, flags);
-
-	return 0;
+	return regmap_update_bits(priv->regmap, offset, mask, val);
 }
 
 static int imx8mp_audiomix_reset_assert(struct reset_controller_dev *rcdev,
@@ -95,6 +83,52 @@ static const struct reset_control_ops imx8mp_audiomix_reset_ops = {
 	.deassert = imx8mp_audiomix_reset_deassert,
 };
 
+static const struct regmap_config regmap_config = {
+	.reg_bits = 32,
+	.val_bits = 32,
+	.reg_stride = 4,
+};
+
+/* assumption: registered only if not using parent regmap */
+static void imx8mp_audiomix_reset_iounmap(void *data)
+{
+	void __iomem *base = (void __iomem *)data;
+
+	iounmap(base);
+}
+
+static int imx8mp_audiomix_reset_get_regmap(struct imx8mp_audiomix_reset *priv)
+{
+	void __iomem *base;
+	struct device *dev;
+	int ret;
+
+	dev = priv->rcdev.dev;
+
+	/* try to use the parent's regmap */
+	priv->regmap = dev_get_regmap(dev->parent, NULL);
+	if (priv->regmap)
+		return 0;
+
+	/* ... if that's not possible then initialize the regmap right now */
+	base = of_iomap(dev->parent->of_node, 0);
+	if (!base)
+		return dev_err_probe(dev, -ENOMEM, "failed to iomap address space\n");
+
+	ret = devm_add_action_or_reset(dev,
+				       imx8mp_audiomix_reset_iounmap,
+				       (void __force *)base);
+	if (ret)
+		return dev_err_probe(dev, ret, "failed to register action\n");
+
+	priv->regmap = devm_regmap_init_mmio(dev, base, &regmap_config);
+	if (IS_ERR(priv->regmap))
+		return dev_err_probe(dev, PTR_ERR(priv->regmap),
+				     "failed to initialize regmap\n");
+
+	return 0;
+}
+
 static int imx8mp_audiomix_reset_probe(struct auxiliary_device *adev,
 				       const struct auxiliary_device_id *id)
 {
@@ -106,36 +140,25 @@ static int imx8mp_audiomix_reset_probe(struct auxiliary_device *adev,
 	if (!priv)
 		return -ENOMEM;
 
-	spin_lock_init(&priv->lock);
-
 	priv->rcdev.owner     = THIS_MODULE;
 	priv->rcdev.nr_resets = ARRAY_SIZE(reset_map);
 	priv->rcdev.ops       = &imx8mp_audiomix_reset_ops;
 	priv->rcdev.of_node   = dev->parent->of_node;
 	priv->rcdev.dev	      = dev;
 	priv->rcdev.of_reset_n_cells = 1;
-	priv->base            = of_iomap(dev->parent->of_node, 0);
-	if (!priv->base)
-		return -ENOMEM;
 
 	dev_set_drvdata(dev, priv);
 
+	ret = imx8mp_audiomix_reset_get_regmap(priv);
+	if (ret)
+		return dev_err_probe(dev, ret, "failed to get regmap\n");
+
 	ret = devm_reset_controller_register(dev, &priv->rcdev);
 	if (ret)
-		goto out_unmap;
+		return dev_err_probe(dev, ret,
+				     "failed to register reset controller\n");
 
 	return 0;
-
-out_unmap:
-	iounmap(priv->base);
-	return ret;
-}
-
-static void imx8mp_audiomix_reset_remove(struct auxiliary_device *adev)
-{
-	struct imx8mp_audiomix_reset *priv = dev_get_drvdata(&adev->dev);
-
-	iounmap(priv->base);
 }
 
 static const struct auxiliary_device_id imx8mp_audiomix_reset_ids[] = {
@@ -148,7 +171,6 @@ MODULE_DEVICE_TABLE(auxiliary, imx8mp_audiomix_reset_ids);
 
 static struct auxiliary_driver imx8mp_audiomix_reset_driver = {
 	.probe		= imx8mp_audiomix_reset_probe,
-	.remove		= imx8mp_audiomix_reset_remove,
 	.id_table	= imx8mp_audiomix_reset_ids,
 };