Date:   Thu, 17 Feb 2022 17:26:33 +0100
From:   Hans de Goede <hans@...sg.org>
To:     Andrey Smirnov <andrew.smirnov@...il.com>,
        platform-driver-x86@...r.kernel.org
Cc:     Mark Gross <markgross@...nel.org>,
        Jean Delvare <jdelvare@...e.com>,
        Guenter Roeck <linux@...ck-us.net>,
        linux-kernel@...r.kernel.org, linux-hwmon@...r.kernel.org
Subject: Re: [PATCH] platform/x86: Add Steam Deck driver

Hi Andrey,

On 2/6/22 03:20, Andrey Smirnov wrote:
> Add a driver exposing various bits and pieces of functionality
> provided by Steam Deck specific VLV0100 device presented by EC
> firmware. This includes but not limited to:
> 
>     - CPU/device's fan control
>     - Read-only access to DDIC registers
>     - Battery tempreature measurements
>     - Various display related control knobs
>     - USB Type-C connector event notification
> 
> Cc: Hans de Goede <hdegoede@...hat.com>
> Cc: Mark Gross <markgross@...nel.org>
> Cc: Jean Delvare <jdelvare@...e.com>
> Cc: Guenter Roeck <linux@...ck-us.net>
> Cc: linux-kernel@...r.kernel.org (open list)
> Cc: platform-driver-x86@...r.kernel.org
> Cc: linux-hwmon@...r.kernel.org
> Signed-off-by: Andrey Smirnov <andrew.smirnov@...il.com>

The .c file says: "Copyright (C) 2021-2022 Valve Corporation"
yet you are using a personal email address. This is not really
an issue, but it does look a bit weird.

> ---
> 
> This driver is really a kitchen sink of various small bits. Maybe it
> is worth splitting into an MFD + child drivers/devices?

Yes with the extcon thing I think you should definitely go for
a MFD device. In which case the main driver registering the
regmap + the cells would go under drivers/mfd and most of the
other drivers would go in their own subsystems.

And as the drivers/platform/x86/ subsystem maintainer I guess
that means I don't have to do much with this driver :)

I would still be happy to yake any bits which don't fit
anywhere else attaching to say a "misc" MFD cell.

Regards,

Hans



> 
>  drivers/platform/x86/Kconfig     |  15 +
>  drivers/platform/x86/Makefile    |   2 +
>  drivers/platform/x86/steamdeck.c | 523 +++++++++++++++++++++++++++++++
>  3 files changed, 540 insertions(+)
>  create mode 100644 drivers/platform/x86/steamdeck.c
> 
> diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
> index c23612d98126..86f014e78a6e 100644
> --- a/drivers/platform/x86/Kconfig
> +++ b/drivers/platform/x86/Kconfig
> @@ -1136,6 +1136,21 @@ config SIEMENS_SIMATIC_IPC
>  	  To compile this driver as a module, choose M here: the module
>  	  will be called simatic-ipc.
> 
> +config STEAMDECK
> +       tristate "Valve Steam Deck platform driver"
> +       depends on X86_64
> +       help
> +         Driver exposing various bits and pieces of functionality
> +	 provided by Steam Deck specific VLV0100 device presented by
> +	 EC firmware. This includes but not limited to:
> +	     - CPU/device's fan control
> +	     - Read-only access to DDIC registers
> +	     - Battery tempreature measurements
> +	     - Various display related control knobs
> +	     - USB Type-C connector event notification
> +
> +	 Say N unless you are running on a Steam Deck.
> +
>  endif # X86_PLATFORM_DEVICES
> 
>  config PMC_ATOM
> diff --git a/drivers/platform/x86/Makefile b/drivers/platform/x86/Makefile
> index c12a9b044fd8..2eb965e14ced 100644
> --- a/drivers/platform/x86/Makefile
> +++ b/drivers/platform/x86/Makefile
> @@ -129,3 +129,5 @@ obj-$(CONFIG_PMC_ATOM)			+= pmc_atom.o
> 
>  # Siemens Simatic Industrial PCs
>  obj-$(CONFIG_SIEMENS_SIMATIC_IPC)	+= simatic-ipc.o
> +
> +obj-$(CONFIG_STEAMDECK)			+= steamdeck.o
> diff --git a/drivers/platform/x86/steamdeck.c b/drivers/platform/x86/steamdeck.c
> new file mode 100644
> index 000000000000..77a6677ec19e
> --- /dev/null
> +++ b/drivers/platform/x86/steamdeck.c
> @@ -0,0 +1,523 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +
> +/*
> + * Steam Deck ACPI platform driver
> + *
> + * Copyright (C) 2021-2022 Valve Corporation
> + *
> + */
> +#include <linux/acpi.h>
> +#include <linux/hwmon.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +#include <linux/extcon-provider.h>
> +
> +#define ACPI_STEAMDECK_NOTIFY_STATUS	0x80
> +
> +/* 0 - port connected, 1 -port disconnected */
> +#define ACPI_STEAMDECK_PORT_CONNECT	BIT(0)
> +/* 0 - Upstream Facing Port, 1 - Downdstream Facing Port */
> +#define ACPI_STEAMDECK_CUR_DATA_ROLE	BIT(3)
> +/*
> + * Debouncing delay to allow negotiation process to settle. 2s value
> + * was arrived at via trial and error.
> + */
> +#define STEAMDECK_ROLE_SWITCH_DELAY	(msecs_to_jiffies(2000))
> +
> +struct steamdeck {
> +	struct acpi_device *adev;
> +	struct device *hwmon;
> +	void *regmap;
> +	long fan_target;
> +	struct delayed_work role_work;
> +	struct extcon_dev *edev;
> +	struct device *dev;
> +};
> +
> +static ssize_t
> +steamdeck_simple_store(struct device *dev, const char *buf, size_t count,
> +		       const char *method,
> +		       unsigned long upper_limit)
> +{
> +	struct steamdeck *fan = dev_get_drvdata(dev);
> +	unsigned long value;
> +
> +	if (kstrtoul(buf, 10, &value) || value >= upper_limit)
> +		return -EINVAL;
> +
> +	if (ACPI_FAILURE(acpi_execute_simple_method(fan->adev->handle,
> +						    (char *)method, value)))
> +		return -EIO;
> +
> +	return count;
> +}
> +
> +#define STEAMDECK_ATTR_WO(_name, _method, _upper_limit)			\
> +	static ssize_t _name##_store(struct device *dev,		\
> +				     struct device_attribute *attr,	\
> +				     const char *buf, size_t count)	\
> +	{								\
> +		return steamdeck_simple_store(dev, buf, count,		\
> +					    _method,			\
> +					    _upper_limit);		\
> +	}								\
> +	static DEVICE_ATTR_WO(_name)
> +
> +STEAMDECK_ATTR_WO(target_cpu_temp, "STCT", U8_MAX / 2);
> +STEAMDECK_ATTR_WO(gain, "SGAN", U16_MAX);
> +STEAMDECK_ATTR_WO(ramp_rate, "SFRR", U8_MAX);
> +STEAMDECK_ATTR_WO(hysteresis, "SHTS",  U16_MAX);
> +STEAMDECK_ATTR_WO(maximum_battery_charge_rate, "CHGR", U16_MAX);
> +STEAMDECK_ATTR_WO(recalculate, "SCHG", U16_MAX);
> +
> +STEAMDECK_ATTR_WO(led_brightness, "CHBV", U8_MAX);
> +STEAMDECK_ATTR_WO(content_adaptive_brightness, "CABC", U8_MAX);
> +STEAMDECK_ATTR_WO(gamma_set, "GAMA", U8_MAX);
> +STEAMDECK_ATTR_WO(display_brightness, "WDBV", U8_MAX);
> +STEAMDECK_ATTR_WO(ctrl_display, "WCDV", U8_MAX);
> +STEAMDECK_ATTR_WO(cabc_minimum_brightness, "WCMB", U8_MAX);
> +STEAMDECK_ATTR_WO(memory_data_access_control, "MDAC", U8_MAX);
> +
> +#define STEAMDECK_ATTR_WO_NOARG(_name, _method)				\
> +	static ssize_t _name##_store(struct device *dev,		\
> +				     struct device_attribute *attr,	\
> +				     const char *buf, size_t count)	\
> +	{								\
> +		struct steamdeck *fan = dev_get_drvdata(dev);		\
> +									\
> +		if (ACPI_FAILURE(acpi_evaluate_object(fan->adev->handle, \
> +						      _method, NULL, NULL))) \
> +			return -EIO;					\
> +									\
> +		return count;						\
> +	}								\
> +	static DEVICE_ATTR_WO(_name)
> +
> +STEAMDECK_ATTR_WO_NOARG(power_cycle_display, "DPCY");
> +STEAMDECK_ATTR_WO_NOARG(display_normal_mode_on, "NORO");
> +STEAMDECK_ATTR_WO_NOARG(display_inversion_off, "INOF");
> +STEAMDECK_ATTR_WO_NOARG(display_inversion_on, "INON");
> +STEAMDECK_ATTR_WO_NOARG(idle_mode_on, "WRNE");
> +
> +#define STEAMDECK_ATTR_RO(_name, _method)				\
> +	static ssize_t _name##_show(struct device *dev,			\
> +				    struct device_attribute *attr,	\
> +				    char *buf)				\
> +	{								\
> +		struct steamdeck *jup = dev_get_drvdata(dev);		\
> +		unsigned long long val;					\
> +									\
> +		if (ACPI_FAILURE(acpi_evaluate_integer(			\
> +					 jup->adev->handle,		\
> +					 _method, NULL, &val)))		\
> +			return -EIO;					\
> +									\
> +		return sprintf(buf, "%llu\n", val);			\
> +	}								\
> +	static DEVICE_ATTR_RO(_name)
> +
> +STEAMDECK_ATTR_RO(firmware_version, "PDFW");
> +STEAMDECK_ATTR_RO(board_id, "BOID");
> +STEAMDECK_ATTR_RO(pdcs, "PDCS");
> +
> +static umode_t
> +steamdeck_is_visible(struct kobject *kobj, struct attribute *attr, int index)
> +{
> +	return attr->mode;
> +}
> +
> +static struct attribute *steamdeck_attributes[] = {
> +	&dev_attr_target_cpu_temp.attr,
> +	&dev_attr_gain.attr,
> +	&dev_attr_ramp_rate.attr,
> +	&dev_attr_hysteresis.attr,
> +	&dev_attr_maximum_battery_charge_rate.attr,
> +	&dev_attr_recalculate.attr,
> +	&dev_attr_power_cycle_display.attr,
> +
> +	&dev_attr_led_brightness.attr,
> +	&dev_attr_content_adaptive_brightness.attr,
> +	&dev_attr_gamma_set.attr,
> +	&dev_attr_display_brightness.attr,
> +	&dev_attr_ctrl_display.attr,
> +	&dev_attr_cabc_minimum_brightness.attr,
> +	&dev_attr_memory_data_access_control.attr,
> +
> +	&dev_attr_display_normal_mode_on.attr,
> +	&dev_attr_display_inversion_off.attr,
> +	&dev_attr_display_inversion_on.attr,
> +	&dev_attr_idle_mode_on.attr,
> +
> +	&dev_attr_firmware_version.attr,
> +	&dev_attr_board_id.attr,
> +	&dev_attr_pdcs.attr,
> +
> +	NULL
> +};
> +
> +static const struct attribute_group steamdeck_group = {
> +	.attrs = steamdeck_attributes,
> +	.is_visible = steamdeck_is_visible,
> +};
> +
> +static const struct attribute_group *steamdeck_groups[] = {
> +	&steamdeck_group,
> +	NULL
> +};
> +
> +static int steamdeck_read_fan_speed(struct steamdeck *jup, long *speed)
> +{
> +	unsigned long long val;
> +
> +	if (ACPI_FAILURE(acpi_evaluate_integer(jup->adev->handle,
> +					       "FANR", NULL, &val)))
> +		return -EIO;
> +
> +	*speed = val;
> +	return 0;
> +}
> +
> +static int
> +steamdeck_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
> +		     u32 attr, int channel, long *out)
> +{
> +	struct steamdeck *sd = dev_get_drvdata(dev);
> +	unsigned long long val;
> +
> +	switch (type) {
> +	case hwmon_temp:
> +		if (attr != hwmon_temp_input)
> +			return -EOPNOTSUPP;
> +
> +		if (ACPI_FAILURE(acpi_evaluate_integer(sd->adev->handle,
> +						       "BATT", NULL, &val)))
> +			return -EIO;
> +		/*
> +		 * Assuming BATT returns deg C we need to mutiply it
> +		 * by 1000 to convert to mC
> +		 */
> +		*out = val * 1000;
> +		break;
> +	case hwmon_fan:
> +		switch (attr) {
> +		case hwmon_fan_input:
> +			return steamdeck_read_fan_speed(sd, out);
> +		case hwmon_fan_target:
> +			*out = sd->fan_target;
> +			break;
> +		case hwmon_fan_fault:
> +			if (ACPI_FAILURE(acpi_evaluate_integer(
> +						 sd->adev->handle,
> +						 "FANC", NULL, &val)))
> +				return -EIO;
> +			/*
> +			 * FANC (Fan check):
> +			 * 0: Abnormal
> +			 * 1: Normal
> +			 */
> +			*out = !val;
> +			break;
> +		default:
> +			return -EOPNOTSUPP;
> +		}
> +		break;
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +
> +	return 0;
> +}
> +
> +static int
> +steamdeck_hwmon_read_string(struct device *dev, enum hwmon_sensor_types type,
> +			    u32 attr, int channel, const char **str)
> +{
> +	switch (type) {
> +	case hwmon_temp:
> +		*str = "Battery Temp";
> +		break;
> +	case hwmon_fan:
> +		*str = "System Fan";
> +		break;
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +
> +	return 0;
> +}
> +
> +static int
> +steamdeck_hwmon_write(struct device *dev, enum hwmon_sensor_types type,
> +		      u32 attr, int channel, long val)
> +{
> +	struct steamdeck *sd = dev_get_drvdata(dev);
> +
> +	if (type != hwmon_fan ||
> +	    attr != hwmon_fan_target)
> +		return -EOPNOTSUPP;
> +
> +	if (val > U16_MAX)
> +		return -EINVAL;
> +
> +	sd->fan_target = val;
> +
> +	if (ACPI_FAILURE(acpi_execute_simple_method(sd->adev->handle,
> +						    "FANS", val)))
> +		return -EIO;
> +
> +	return 0;
> +}
> +
> +static umode_t
> +steamdeck_hwmon_is_visible(const void *data, enum hwmon_sensor_types type,
> +			   u32 attr, int channel)
> +{
> +	if (type == hwmon_fan &&
> +	    attr == hwmon_fan_target)
> +		return 0644;
> +
> +	return 0444;
> +}
> +
> +static const struct hwmon_channel_info *steamdeck_info[] = {
> +	HWMON_CHANNEL_INFO(temp,
> +			   HWMON_T_INPUT | HWMON_T_LABEL),
> +	HWMON_CHANNEL_INFO(fan,
> +			   HWMON_F_INPUT | HWMON_F_LABEL |
> +			   HWMON_F_TARGET | HWMON_F_FAULT),
> +	NULL
> +};
> +
> +static const struct hwmon_ops steamdeck_hwmon_ops = {
> +	.is_visible = steamdeck_hwmon_is_visible,
> +	.read = steamdeck_hwmon_read,
> +	.read_string = steamdeck_hwmon_read_string,
> +	.write = steamdeck_hwmon_write,
> +};
> +
> +static const struct hwmon_chip_info steamdeck_chip_info = {
> +	.ops = &steamdeck_hwmon_ops,
> +	.info = steamdeck_info,
> +};
> +
> +#define STEAMDECK_STA_OK			\
> +	(ACPI_STA_DEVICE_ENABLED |		\
> +	 ACPI_STA_DEVICE_PRESENT |		\
> +	 ACPI_STA_DEVICE_FUNCTIONING)
> +
> +static int
> +steamdeck_ddic_reg_read(void *context, unsigned int reg, unsigned int *val)
> +{
> +	union acpi_object obj = { .type = ACPI_TYPE_INTEGER };
> +	struct acpi_object_list arg_list = { .count = 1, .pointer = &obj, };
> +	struct steamdeck *sd = context;
> +	unsigned long long _val;
> +
> +	obj.integer.value = reg;
> +
> +	if (ACPI_FAILURE(acpi_evaluate_integer(sd->adev->handle,
> +					       "RDDI", &arg_list, &_val)))
> +		return -EIO;
> +
> +	*val = _val;
> +	return 0;
> +}
> +
> +static int steamdeck_read_pdcs(struct steamdeck *sd, unsigned long long *pdcs)
> +{
> +	acpi_status status;
> +
> +	status = acpi_evaluate_integer(sd->adev->handle, "PDCS", NULL, pdcs);
> +	if (ACPI_FAILURE(status)) {
> +		dev_err(sd->dev, "PDCS evaluation failed: %s\n",
> +			acpi_format_exception(status));
> +		return -EIO;
> +	}
> +
> +	return 0;
> +}
> +
> +static void steamdeck_usb_role_work(struct work_struct *work)
> +{
> +	struct steamdeck *sd =
> +		container_of(work, struct steamdeck, role_work.work);
> +	unsigned long long pdcs;
> +	bool usb_host;
> +
> +	if (steamdeck_read_pdcs(sd, &pdcs))
> +		return;
> +
> +	/*
> +	 * We only care about these two
> +	 */
> +	pdcs &= ACPI_STEAMDECK_PORT_CONNECT | ACPI_STEAMDECK_CUR_DATA_ROLE;
> +
> +	/*
> +	 * For "connect" events our role is determined by a bit in
> +	 * PDCS, for "disconnect" we switch to being a gadget
> +	 * unconditionally. The thinking for the latter is we don't
> +	 * want to start acting as a USB host until we get
> +	 * confirmation from the firmware that we are a USB host
> +	 */
> +	usb_host = (pdcs & ACPI_STEAMDECK_PORT_CONNECT) ?
> +		pdcs & ACPI_STEAMDECK_CUR_DATA_ROLE : false;
> +
> +	WARN_ON(extcon_set_state_sync(sd->edev, EXTCON_USB_HOST,
> +				      usb_host));
> +	dev_dbg(sd->dev, "USB role is %s\n", usb_host ? "host" : "device");
> +}
> +
> +static void steamdeck_notify(acpi_handle handle, u32 event, void *context)
> +{
> +	struct device *dev = context;
> +	struct steamdeck *sd = dev_get_drvdata(dev);
> +	unsigned long long pdcs;
> +	unsigned long delay;
> +
> +	switch (event) {
> +	case ACPI_STEAMDECK_NOTIFY_STATUS:
> +		if (steamdeck_read_pdcs(sd, &pdcs))
> +			return;
> +		/*
> +		 * We process "disconnect" events immediately and
> +		 * "connect" events with a delay to give the HW time
> +		 * to settle. For example attaching USB hub (at least
> +		 * for HW used for testing) will generate intermediary
> +		 * event with "host" bit not set, followed by the one
> +		 * that does have it set.
> +		 */
> +		delay = (pdcs & ACPI_STEAMDECK_PORT_CONNECT) ?
> +			STEAMDECK_ROLE_SWITCH_DELAY : 0;
> +
> +		queue_delayed_work(system_long_wq, &sd->role_work, delay);
> +		break;
> +	default:
> +		dev_err(dev, "Unsupported event [0x%x]\n", event);
> +	}
> +}
> +
> +static void steamdeck_remove_notify_handler(void *data)
> +{
> +	struct steamdeck *sd = data;
> +
> +	acpi_remove_notify_handler(sd->adev->handle, ACPI_DEVICE_NOTIFY,
> +				   steamdeck_notify);
> +	cancel_delayed_work_sync(&sd->role_work);
> +}
> +
> +static const unsigned int steamdeck_extcon_cable[] = {
> +	EXTCON_USB,
> +	EXTCON_USB_HOST,
> +	EXTCON_CHG_USB_SDP,
> +	EXTCON_CHG_USB_CDP,
> +	EXTCON_CHG_USB_DCP,
> +	EXTCON_CHG_USB_ACA,
> +	EXTCON_NONE,
> +};
> +
> +static int steamdeck_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct steamdeck *sd;
> +	acpi_status status;
> +	unsigned long long sta;
> +	int ret;
> +
> +	static const struct regmap_config regmap_config = {
> +		.reg_bits = 8,
> +		.val_bits = 8,
> +		.max_register = 255,
> +		.cache_type = REGCACHE_NONE,
> +		.reg_read = steamdeck_ddic_reg_read,
> +	};
> +
> +	sd = devm_kzalloc(dev, sizeof(*sd), GFP_KERNEL);
> +	if (!sd)
> +		return -ENOMEM;
> +	sd->adev = ACPI_COMPANION(&pdev->dev);
> +	sd->dev = dev;
> +	platform_set_drvdata(pdev, sd);
> +	INIT_DELAYED_WORK(&sd->role_work, steamdeck_usb_role_work);
> +
> +	status = acpi_evaluate_integer(sd->adev->handle, "_STA",
> +				       NULL, &sta);
> +	if (ACPI_FAILURE(status)) {
> +		dev_err(dev, "Status check failed (0x%x)\n", status);
> +		return -EINVAL;
> +	}
> +
> +	if ((sta & STEAMDECK_STA_OK) != STEAMDECK_STA_OK) {
> +		dev_err(dev, "Device is not ready\n");
> +		return -EINVAL;
> +	}
> +
> +	/*
> +	 * Our ACPI interface doesn't expose a method to read current
> +	 * fan target, so we use current fan speed as an
> +	 * approximation.
> +	 */
> +	if (steamdeck_read_fan_speed(sd, &sd->fan_target))
> +		dev_warn(dev, "Failed to read fan speed");
> +
> +	sd->hwmon = devm_hwmon_device_register_with_info(dev,
> +							 "steamdeck",
> +							 sd,
> +							 &steamdeck_chip_info,
> +							 steamdeck_groups);
> +	if (IS_ERR(sd->hwmon)) {
> +		dev_err(dev, "Failed to register HWMON device");
> +		return PTR_ERR(sd->hwmon);
> +	}
> +
> +	sd->regmap = devm_regmap_init(dev, NULL, sd, &regmap_config);
> +	if (IS_ERR(sd->regmap))
> +		dev_err(dev, "Failed to register REGMAP");
> +
> +	sd->edev = devm_extcon_dev_allocate(dev, steamdeck_extcon_cable);
> +	if (IS_ERR(sd->edev))
> +		return -ENOMEM;
> +
> +	ret = devm_extcon_dev_register(dev, sd->edev);
> +	if (ret < 0) {
> +		dev_err(dev, "Failed to register extcon device: %d\n", ret);
> +		return ret;
> +	}
> +
> +	/*
> +	 * Set initial role value
> +	 */
> +	queue_delayed_work(system_long_wq, &sd->role_work, 0);
> +	flush_delayed_work(&sd->role_work);
> +
> +	status = acpi_install_notify_handler(sd->adev->handle,
> +					     ACPI_DEVICE_NOTIFY,
> +					     steamdeck_notify,
> +					     dev);
> +	if (ACPI_FAILURE(status)) {
> +		dev_err(dev, "Error installing ACPI notify handler\n");
> +		return -EIO;
> +	}
> +
> +	ret = devm_add_action_or_reset(dev, steamdeck_remove_notify_handler,
> +				       sd);
> +	return ret;
> +}
> +
> +static const struct acpi_device_id steamdeck_device_ids[] = {
> +	{ "VLV0100", 0 },
> +	{ "", 0 },
> +};
> +MODULE_DEVICE_TABLE(acpi, steamdeck_device_ids);
> +
> +static struct platform_driver steamdeck_driver = {
> +	.probe = steamdeck_probe,
> +	.driver = {
> +		.name = "steamdeck",
> +		.acpi_match_table = steamdeck_device_ids,
> +	},
> +};
> +module_platform_driver(steamdeck_driver);
> +
> +MODULE_AUTHOR("Andrey Smirnov <andrew.smirnov@...il.com>");
> +MODULE_DESCRIPTION("Steam Deck ACPI platform driver");
> +MODULE_LICENSE("GPL");
> --
> 2.25.1
> 

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