Re: [PATCH v4 5/8] reset: imx8mp-audiomix: Switch to using regmap API

[Frank Li <Frank.li@nxp.com>]

On Wed, Nov 05, 2025 at 03:53:59AM -0800, Laurentiu Mihalcea wrote:
>
> On 11/4/2025 8:44 AM, Frank Li wrote:
> > On Tue, Nov 04, 2025 at 04:02:58AM -0800, Laurentiu Mihalcea wrote:
> >> From: Laurentiu Mihalcea <laurentiu.mihalcea@nxp.com>
> >>
> >> 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.
> >>
> >> Signed-off-by: Laurentiu Mihalcea <laurentiu.mihalcea@nxp.com>
> >> ---
> >>  drivers/reset/reset-imx8mp-audiomix.c | 93 +++++++++++++++++----------
> >>  1 file changed, 58 insertions(+), 35 deletions(-)
> >>
> >> diff --git a/drivers/reset/reset-imx8mp-audiomix.c b/drivers/reset/reset-imx8mp-audiomix.c
> >> index e9643365a62c..18a7f68aa59f 100644
> >> --- a/drivers/reset/reset-imx8mp-audiomix.c
> >> +++ b/drivers/reset/reset-imx8mp-audiomix.c
> >> @@ -11,6 +11,7 @@
> >>  #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
> >> @@ -42,8 +43,7 @@ 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)
> >> @@ -55,26 +55,15 @@ 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, shift, val;
> >>
> >>  	mask = reset_map[id].mask;
> >>  	offset = reset_map[id].offset;
> >>  	active_low = reset_map[id].active_low;
> >> +	shift = ffs(mask) - 1;
> >> +	val = (active_low ^ assert) << shift;
> >>
> >> -	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,
> >> @@ -94,6 +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");
> > Does anyone still base?  Supposed aux device probed by parent devices,
> > if all parent already switch to regmap, you can remove this part.
> >
> > Frank
>
>
> both clk-imx8ulp-sim-lpav and clk-imx8mp-audiomix don't handle the clock gate
>
> functionality by themselves. Instead, they use the generic clock gate driver, which
>
> doesn't use regmap. ATM, I don't plan on extending that to use regmap (how would
>
> that work? would we want that? would it be useful for other people as well?)

Okay, I suppose parent clock driver use iomap also, which cause map the
same area twice. Although it works, I think it'd better pass down mapped
address to this driver. Anyways you may improve later.

Frank

>