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From:   Andrey Smirnov <andrew.smirnov@gmail.com>
To:     platform-driver-x86@vger.kernel.org
Cc:     Andrey Smirnov <andrew.smirnov@gmail.com>,
        Hans de Goede <hdegoede@redhat.com>,
        Mark Gross <markgross@kernel.org>,
        Jean Delvare <jdelvare@suse.com>,
        Guenter Roeck <linux@roeck-us.net>,
        linux-kernel@vger.kernel.org, linux-hwmon@vger.kernel.org
Subject: [PATCH] platform/x86: Add Steam Deck driver
Date:   Sat,  5 Feb 2022 18:20:23 -0800
Message-Id: <20220206022023.376142-1-andrew.smirnov@gmail.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

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@redhat.com>
Cc: Mark Gross <markgross@kernel.org>
Cc: Jean Delvare <jdelvare@suse.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: linux-kernel@vger.kernel.org (open list)
Cc: platform-driver-x86@vger.kernel.org
Cc: linux-hwmon@vger.kernel.org
Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
---

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

 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@gmail.com>");
+MODULE_DESCRIPTION("Steam Deck ACPI platform driver");
+MODULE_LICENSE("GPL");
--
2.25.1