Re: [PATCH v5 06/10] gpio: Add new gpio-macsmc driver for Apple Macs

[Alyssa Rosenzweig <alyssa@rosenzweig.io>]

Reviewed-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>

Le Sun , May 11, 2025 at 08:18:41AM +0000, Sven Peter via B4 Relay a écrit :
> From: Hector Martin <marcan@marcan.st>
> 
> This driver implements the GPIO service on top of the SMC framework
> on Apple Mac machines. In particular, these are the GPIOs present in the
> PMU IC which are used to control power to certain on-board devices.
> 
> Although the underlying hardware supports various pin config settings
> (input/output, open drain, etc.), this driver does not implement that
> functionality and leaves it up to the firmware to configure things
> properly. We also don't yet support interrupts/events. This is
> sufficient for device power control, which is the only thing we need to
> support at this point. More features will be implemented when needed.
> 
> To our knowledge, only Apple Silicon Macs implement this SMC feature.
> 
> Signed-off-by: Hector Martin <marcan@marcan.st>
> Reviewed-by: Bartosz Golaszewski <brgl@bgdev.pl>
> Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
> Reviewed-by: Sven Peter <sven@svenpeter.dev>
> Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
> Signed-off-by: Sven Peter <sven@svenpeter.dev>
> ---
>  MAINTAINERS                |   1 +
>  drivers/gpio/Kconfig       |  10 ++
>  drivers/gpio/Makefile      |   1 +
>  drivers/gpio/gpio-macsmc.c | 293 +++++++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 305 insertions(+)
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index dfaca531600c22d487fb17a25294686611dd4513..fa3a5f9ee40446bcc725c9eac2a36651e6bc7553 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -2291,6 +2291,7 @@ F:	drivers/bluetooth/hci_bcm4377.c
>  F:	drivers/clk/clk-apple-nco.c
>  F:	drivers/cpufreq/apple-soc-cpufreq.c
>  F:	drivers/dma/apple-admac.c
> +F:	drivers/gpio/gpio-macsmc.c
>  F:	drivers/pmdomain/apple/
>  F:	drivers/i2c/busses/i2c-pasemi-core.c
>  F:	drivers/i2c/busses/i2c-pasemi-platform.c
> diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
> index f2c39bbff83a33dcb12b2d32aa3ebc358a0dd949..f0e25105f8ebe7356344722987333a9fc244ea1f 100644
> --- a/drivers/gpio/Kconfig
> +++ b/drivers/gpio/Kconfig
> @@ -1440,6 +1440,16 @@ config GPIO_LP87565
>  	  This driver can also be built as a module. If so, the module will be
>  	  called gpio-lp87565.
>  
> +config GPIO_MACSMC
> +	tristate "Apple Mac SMC GPIO"
> +	depends on MFD_MACSMC
> +	help
> +	  Support for GPIOs controlled by the SMC microcontroller on Apple Mac
> +	  systems.
> +
> +	  This driver can also be built as a module. If so, the module will be
> +	  called gpio-macsmc.
> +
>  config GPIO_MADERA
>  	tristate "Cirrus Logic Madera class codecs"
>  	depends on PINCTRL_MADERA
> diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
> index af130882ffeeef8b1d518867bfe1493ec4f21b5f..c2e47f356bfae73384ace8103074f246e49fb9d6 100644
> --- a/drivers/gpio/Makefile
> +++ b/drivers/gpio/Makefile
> @@ -97,6 +97,7 @@ obj-$(CONFIG_GPIO_LP873X)		+= gpio-lp873x.o
>  obj-$(CONFIG_GPIO_LP87565)		+= gpio-lp87565.o
>  obj-$(CONFIG_GPIO_LPC18XX)		+= gpio-lpc18xx.o
>  obj-$(CONFIG_GPIO_LPC32XX)		+= gpio-lpc32xx.o
> +obj-$(CONFIG_GPIO_MACSMC)		+= gpio-macsmc.o
>  obj-$(CONFIG_GPIO_MADERA)		+= gpio-madera.o
>  obj-$(CONFIG_GPIO_MAX3191X)		+= gpio-max3191x.o
>  obj-$(CONFIG_GPIO_MAX7300)		+= gpio-max7300.o
> diff --git a/drivers/gpio/gpio-macsmc.c b/drivers/gpio/gpio-macsmc.c
> new file mode 100644
> index 0000000000000000000000000000000000000000..bb179c71a05e294c9ec68db332ad4c0dff118d1a
> --- /dev/null
> +++ b/drivers/gpio/gpio-macsmc.c
> @@ -0,0 +1,293 @@
> +// SPDX-License-Identifier: GPL-2.0-only OR MIT
> +/*
> + * Apple SMC GPIO driver
> + * Copyright The Asahi Linux Contributors
> + *
> + * This driver implements basic SMC PMU GPIO support that can read inputs
> + * and write outputs. Mode changes and IRQ config are not yet implemented.
> + */
> +
> +#include <linux/bitmap.h>
> +#include <linux/device.h>
> +#include <linux/gpio/driver.h>
> +#include <linux/mfd/core.h>
> +#include <linux/mfd/macsmc.h>
> +
> +#define MAX_GPIO 64
> +
> +/*
> + * Commands 0-6 are, presumably, the intended API.
> + * Command 0xff lets you get/set the pin configuration in detail directly,
> + * but the bit meanings seem not to be stable between devices/PMU hardware
> + * versions.
> + *
> + * We're going to try to make do with the low commands for now.
> + * We don't implement pin mode changes at this time.
> + */
> +
> +#define CMD_ACTION	(0 << 24)
> +#define CMD_OUTPUT	(1 << 24)
> +#define CMD_INPUT	(2 << 24)
> +#define CMD_PINMODE	(3 << 24)
> +#define CMD_IRQ_ENABLE	(4 << 24)
> +#define CMD_IRQ_ACK	(5 << 24)
> +#define CMD_IRQ_MODE	(6 << 24)
> +#define CMD_CONFIG	(0xff << 24)
> +
> +#define MODE_INPUT	0
> +#define MODE_OUTPUT	1
> +#define MODE_VALUE_0	0
> +#define MODE_VALUE_1	2
> +
> +#define IRQ_MODE_HIGH		0
> +#define IRQ_MODE_LOW		1
> +#define IRQ_MODE_RISING		2
> +#define IRQ_MODE_FALLING	3
> +#define IRQ_MODE_BOTH		4
> +
> +#define CONFIG_MASK	GENMASK(23, 16)
> +#define CONFIG_VAL	GENMASK(7, 0)
> +
> +#define CONFIG_OUTMODE	GENMASK(7, 6)
> +#define CONFIG_IRQMODE	GENMASK(5, 3)
> +#define CONFIG_PULLDOWN	BIT(2)
> +#define CONFIG_PULLUP	BIT(1)
> +#define CONFIG_OUTVAL	BIT(0)
> +
> +/*
> + * Output modes seem to differ depending on the PMU in use... ?
> + * j274 / M1 (Sera PMU):
> + *   0 = input
> + *   1 = output
> + *   2 = open drain
> + *   3 = disable
> + * j314 / M1Pro (Maverick PMU):
> + *   0 = input
> + *   1 = open drain
> + *   2 = output
> + *   3 = ?
> + */
> +
> +struct macsmc_gpio {
> +	struct device *dev;
> +	struct apple_smc *smc;
> +	struct gpio_chip gc;
> +
> +	int first_index;
> +};
> +
> +static int macsmc_gpio_nr(smc_key key)
> +{
> +	int low = hex_to_bin(key & 0xff);
> +	int high = hex_to_bin((key >> 8) & 0xff);
> +
> +	if (low < 0 || high < 0)
> +		return -1;
> +
> +	return low | (high << 4);
> +}
> +
> +static int macsmc_gpio_key(unsigned int offset)
> +{
> +	return _SMC_KEY("gP\0\0") | hex_asc_hi(offset) << 8 | hex_asc_lo(offset);
> +}
> +
> +static int macsmc_gpio_find_first_gpio_index(struct macsmc_gpio *smcgp)
> +{
> +	struct apple_smc *smc = smcgp->smc;
> +	smc_key key = macsmc_gpio_key(0);
> +	smc_key first_key, last_key;
> +	int start, count, ret;
> +
> +	/* Return early if the key is out of bounds */
> +	ret = apple_smc_get_key_by_index(smc, 0, &first_key);
> +	if (ret)
> +		return ret;
> +	if (key <= first_key)
> +		return -ENODEV;
> +
> +	ret = apple_smc_get_key_by_index(smc, smc->key_count - 1, &last_key);
> +	if (ret)
> +		return ret;
> +	if (key > last_key)
> +		return -ENODEV;
> +
> +	/* Binary search to find index of first SMC key bigger or equal to key */
> +	start = 0;
> +	count = smc->key_count;
> +	while (count > 1) {
> +		smc_key pkey;
> +		int pivot = start + ((count - 1) >> 1);
> +
> +		ret = apple_smc_get_key_by_index(smc, pivot, &pkey);
> +		if (ret < 0)
> +			return ret;
> +
> +		if (pkey == key)
> +			return pivot;
> +
> +		pivot++;
> +
> +		if (pkey < key) {
> +			count -= pivot - start;
> +			start = pivot;
> +		} else {
> +			count = pivot - start;
> +		}
> +	}
> +
> +	return start;
> +}
> +
> +static int macsmc_gpio_get_direction(struct gpio_chip *gc, unsigned int offset)
> +{
> +	struct macsmc_gpio *smcgp = gpiochip_get_data(gc);
> +	smc_key key = macsmc_gpio_key(offset);
> +	u32 val;
> +	int ret;
> +
> +	/* First try reading the explicit pin mode register */
> +	ret = apple_smc_rw_u32(smcgp->smc, key, CMD_PINMODE, &val);
> +	if (!ret)
> +		return (val & MODE_OUTPUT) ? GPIO_LINE_DIRECTION_OUT : GPIO_LINE_DIRECTION_IN;
> +
> +	/*
> +	 * Less common IRQ configs cause CMD_PINMODE to fail, and so does open drain mode.
> +	 * Fall back to reading IRQ mode, which will only succeed for inputs.
> +	 */
> +	ret = apple_smc_rw_u32(smcgp->smc, key, CMD_IRQ_MODE, &val);
> +	return ret ? GPIO_LINE_DIRECTION_OUT : GPIO_LINE_DIRECTION_IN;
> +}
> +
> +static int macsmc_gpio_get(struct gpio_chip *gc, unsigned int offset)
> +{
> +	struct macsmc_gpio *smcgp = gpiochip_get_data(gc);
> +	smc_key key = macsmc_gpio_key(offset);
> +	u32 cmd, val;
> +	int ret;
> +
> +	ret = macsmc_gpio_get_direction(gc, offset);
> +	if (ret < 0)
> +		return ret;
> +
> +	if (ret == GPIO_LINE_DIRECTION_OUT)
> +		cmd = CMD_OUTPUT;
> +	else
> +		cmd = CMD_INPUT;
> +
> +	ret = apple_smc_rw_u32(smcgp->smc, key, cmd, &val);
> +	if (ret < 0)
> +		return ret;
> +
> +	return val ? 1 : 0;
> +}
> +
> +static int macsmc_gpio_set(struct gpio_chip *gc, unsigned int offset, int value)
> +{
> +	struct macsmc_gpio *smcgp = gpiochip_get_data(gc);
> +	smc_key key = macsmc_gpio_key(offset);
> +	int ret;
> +
> +	value |= CMD_OUTPUT;
> +	ret = apple_smc_write_u32(smcgp->smc, key, CMD_OUTPUT | value);
> +	if (ret < 0)
> +		dev_err(smcgp->dev, "GPIO set failed %p4ch = 0x%x\n",
> +			&key, value);
> +
> +	return ret;
> +}
> +
> +static int macsmc_gpio_init_valid_mask(struct gpio_chip *gc,
> +				       unsigned long *valid_mask, unsigned int ngpios)
> +{
> +	struct macsmc_gpio *smcgp = gpiochip_get_data(gc);
> +	int count;
> +	int i;
> +
> +	count = min(smcgp->smc->key_count, MAX_GPIO);
> +
> +	bitmap_zero(valid_mask, ngpios);
> +
> +	for (i = 0; i < count; i++) {
> +		int ret, gpio_nr;
> +		smc_key key;
> +
> +		ret = apple_smc_get_key_by_index(smcgp->smc, smcgp->first_index + i, &key);
> +		if (ret < 0)
> +			return ret;
> +
> +		if (key > SMC_KEY(gPff))
> +			break;
> +
> +		gpio_nr = macsmc_gpio_nr(key);
> +		if (gpio_nr < 0 || gpio_nr > MAX_GPIO) {
> +			dev_err(smcgp->dev, "Bad GPIO key %p4ch\n", &key);
> +			continue;
> +		}
> +
> +		set_bit(gpio_nr, valid_mask);
> +	}
> +
> +	return 0;
> +}
> +
> +static int macsmc_gpio_probe(struct platform_device *pdev)
> +{
> +	struct macsmc_gpio *smcgp;
> +	struct apple_smc *smc = dev_get_drvdata(pdev->dev.parent);
> +	smc_key key;
> +	int ret;
> +
> +	smcgp = devm_kzalloc(&pdev->dev, sizeof(*smcgp), GFP_KERNEL);
> +	if (!smcgp)
> +		return -ENOMEM;
> +
> +	smcgp->dev = &pdev->dev;
> +	smcgp->smc = smc;
> +
> +	smcgp->first_index = macsmc_gpio_find_first_gpio_index(smcgp);
> +	if (smcgp->first_index < 0)
> +		return smcgp->first_index;
> +
> +	ret = apple_smc_get_key_by_index(smc, smcgp->first_index, &key);
> +	if (ret < 0)
> +		return ret;
> +
> +	if (key > macsmc_gpio_key(MAX_GPIO - 1))
> +		return -ENODEV;
> +
> +	dev_info(smcgp->dev, "First GPIO key: %p4ch\n", &key);
> +
> +	smcgp->gc.label = "macsmc-pmu-gpio";
> +	smcgp->gc.owner = THIS_MODULE;
> +	smcgp->gc.get = macsmc_gpio_get;
> +	smcgp->gc.set_rv = macsmc_gpio_set;
> +	smcgp->gc.get_direction = macsmc_gpio_get_direction;
> +	smcgp->gc.init_valid_mask = macsmc_gpio_init_valid_mask;
> +	smcgp->gc.can_sleep = true;
> +	smcgp->gc.ngpio = MAX_GPIO;
> +	smcgp->gc.base = -1;
> +	smcgp->gc.parent = &pdev->dev;
> +
> +	return devm_gpiochip_add_data(&pdev->dev, &smcgp->gc, smcgp);
> +}
> +
> +static const struct of_device_id macsmc_gpio_of_table[] = {
> +	{ .compatible = "apple,smc-gpio", },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(of, macsmc_gpio_of_table);
> +
> +static struct platform_driver macsmc_gpio_driver = {
> +	.driver = {
> +		.name = "macsmc-gpio",
> +		.of_match_table = macsmc_gpio_of_table,
> +	},
> +	.probe = macsmc_gpio_probe,
> +};
> +module_platform_driver(macsmc_gpio_driver);
> +
> +MODULE_AUTHOR("Hector Martin <marcan@marcan.st>");
> +MODULE_LICENSE("Dual MIT/GPL");
> +MODULE_DESCRIPTION("Apple SMC GPIO driver");
> +MODULE_ALIAS("platform:macsmc-gpio");
> 
> -- 
> 2.34.1
> 
>