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

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Message-ID: <e7481838-af1a-46ad-9f94-8de4e20a9611@gmail.com>
Date: Wed, 5 Nov 2025 03:53:59 -0800
From: Laurentiu Mihalcea <laurentiumihalcea111@...il.com>
To: Frank Li <Frank.li@....com>
Cc: Abel Vesa <abelvesa@...nel.org>,
 Michael Turquette <mturquette@...libre.com>, Stephen Boyd
 <sboyd@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>, Shawn Guo <shawnguo@...nel.org>,
 Fabio Estevam <festevam@...il.com>, Philipp Zabel <p.zabel@...gutronix.de>,
 Daniel Baluta <daniel.baluta@....com>, Shengjiu Wang
 <shengjiu.wang@....com>, linux-clk@...r.kernel.org, imx@...ts.linux.dev,
 devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 linux-kernel@...r.kernel.org, Pengutronix Kernel Team <kernel@...gutronix.de>
Subject: Re: [PATCH v4 5/8] reset: imx8mp-audiomix: Switch to using regmap API


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@....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@....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?)