platform/x86: surface3_power: MSHW0011 rev-eng implementation

Patch was rebased on top of for-next. Thanks for your patience!

Blaž

I'm resubmitting this patch with review feedback addressed:

https://patchwork.kernel.org/patch/10584079/

The patch was previously not resubmitted because it required a change
that was reverted in the ACPICA. That has since been corrected:

https://github.com/acpica/acpica/commit/9159c09a2a5897a43f78c95cdffc160d399722c3

We've been using this patch for a while and user reports confirm that it
works:

https://github.com/linux-surface/linux-surface

Previous description follows.

>8------------------------------------------------------8<

The MSHW0011 device is a chip that replaces the battery firmware
by using ACPI operation regions on the Surface 3.
It is unclear whether or not the chip will be reused somewhere else
(under Windows, the chip is called "Surface Platform Power Driver"
and the driver is provided by Microsoft).

The values have been obtained by reverse engineering, and are subject to
errors. Looks like it works on overall pretty well.

I couldn't manage to get the IRQ correctly triggered, so I am using a
good old polling thread to check for changes. This is something
to be fixed in a later version.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=106231Signed-off-by: Blaž Hrastnik <blaz@mxxn.io>
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Stephen Just <stephenjust@gmail.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

drivers/platform/x86/Kconfig

@@ -861,6 +861,13 @@ config SURFACE_PRO3_BUTTON
 	---help---
 	  This driver handles the power/home/volume buttons on the Microsoft Surface Pro 3/4 tablet.
 
+config SURFACE_3_POWER_OPREGION
+	tristate "Surface 3 battery platform operation region support"
+	depends on ACPI && I2C
+	help
+	  This driver provides support for ACPI operation
+	  region of the Surface 3 battery platform driver.
+
 config MSI_LAPTOP
 	tristate "MSI Laptop Extras"
 	depends on ACPI

drivers/platform/x86/Makefile

@@ -82,6 +82,7 @@ obj-$(CONFIG_INTEL_VBTN)		+= intel-vbtn.o
 # Microsoft
 obj-$(CONFIG_SURFACE3_WMI)		+= surface3-wmi.o
 obj-$(CONFIG_SURFACE_3_BUTTON)		+= surface3_button.o
+obj-$(CONFIG_SURFACE_3_POWER_OPREGION)	+= surface3_power.o
 obj-$(CONFIG_SURFACE_PRO3_BUTTON)	+= surfacepro3_button.o
 
 # MSI

drivers/platform/x86/surface3_power.c

+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Supports for the power IC on the Surface 3 tablet.
+ *
+ * (C) Copyright 2016-2018 Red Hat, Inc
+ * (C) Copyright 2016-2018 Benjamin Tissoires <benjamin.tissoires@gmail.com>
+ * (C) Copyright 2016 Stephen Just <stephenjust@gmail.com>
+ *
+ * This driver has been reverse-engineered by parsing the DSDT of the Surface 3
+ * and looking at the registers of the chips.
+ *
+ * The DSDT allowed to find out that:
+ * - the driver is required for the ACPI BAT0 device to communicate to the chip
+ *   through an operation region.
+ * - the various defines for the operation region functions to communicate with
+ *   this driver
+ * - the DSM 3f99e367-6220-4955-8b0f-06ef2ae79412 allows to trigger ACPI
+ *   events to BAT0 (the code is all available in the DSDT).
+ *
+ * Further findings regarding the 2 chips declared in the MSHW0011 are:
+ * - there are 2 chips declared:
+ *   . 0x22 seems to control the ADP1 line status (and probably the charger)
+ *   . 0x55 controls the battery directly
+ * - the battery chip uses a SMBus protocol (using plain SMBus allows non
+ *   destructive commands):
+ *   . the commands/registers used are in the range 0x00..0x7F
+ *   . if bit 8 (0x80) is set in the SMBus command, the returned value is the
+ *     same as when it is not set. There is a high chance this bit is the
+ *     read/write
+ *   . the various registers semantic as been deduced by observing the register
+ *     dumps.
+ */
+
+#include <linux/acpi.h>
+#include <linux/freezer.h>
+#include <linux/i2c.h>
+#include <linux/kernel.h>
+#include <linux/kthread.h>
+#include <linux/slab.h>
+#include <linux/uuid.h>
+#include <asm/unaligned.h>
+
+#define POLL_INTERVAL		(2 * HZ)
+#define SURFACE_3_STRLEN 10
+
+struct mshw0011_data {
+	struct i2c_client	*adp1;
+	struct i2c_client	*bat0;
+	unsigned short		notify_mask;
+	struct task_struct	*poll_task;
+	bool			kthread_running;
+
+	bool			charging;
+	bool			bat_charging;
+	u8			trip_point;
+	s32			full_capacity;
+};
+
+struct mshw0011_lookup {
+	struct mshw0011_data	*cdata;
+	unsigned int		n;
+	unsigned int		index;
+	int			addr;
+};
+
+struct mshw0011_handler_data {
+	struct acpi_connection_info	info;
+	struct i2c_client		*client;
+};
+
+struct bix {
+	u32	revision;
+	u32	power_unit;
+	u32	design_capacity;
+	u32	last_full_charg_capacity;
+	u32	battery_technology;
+	u32	design_voltage;
+	u32	design_capacity_of_warning;
+	u32	design_capacity_of_low;
+	u32	cycle_count;
+	u32	measurement_accuracy;
+	u32	max_sampling_time;
+	u32	min_sampling_time;
+	u32	max_average_interval;
+	u32	min_average_interval;
+	u32	battery_capacity_granularity_1;
+	u32	battery_capacity_granularity_2;
+	char	model[SURFACE_3_STRLEN];
+	char	serial[SURFACE_3_STRLEN];
+	char	type[SURFACE_3_STRLEN];
+	char	OEM[SURFACE_3_STRLEN];
+} __packed;
+
+struct bst {
+	u32	battery_state;
+	s32	battery_present_rate;
+	u32	battery_remaining_capacity;
+	u32	battery_present_voltage;
+} __packed;
+
+struct gsb_command {
+	u8	arg0;
+	u8	arg1;
+	u8	arg2;
+} __packed;
+
+struct gsb_buffer {
+	u8	status;
+	u8	len;
+	u8	ret;
+	union {
+		struct gsb_command	cmd;
+		struct bst		bst;
+		struct bix		bix;
+	} __packed;
+} __packed;
+
+#define ACPI_BATTERY_STATE_DISCHARGING	BIT(0)
+#define ACPI_BATTERY_STATE_CHARGING	BIT(1)
+#define ACPI_BATTERY_STATE_CRITICAL	BIT(2)
+
+#define MSHW0011_CMD_DEST_BAT0		0x01
+#define MSHW0011_CMD_DEST_ADP1		0x03
+
+#define MSHW0011_CMD_BAT0_STA		0x01
+#define MSHW0011_CMD_BAT0_BIX		0x02
+#define MSHW0011_CMD_BAT0_BCT		0x03
+#define MSHW0011_CMD_BAT0_BTM		0x04
+#define MSHW0011_CMD_BAT0_BST		0x05
+#define MSHW0011_CMD_BAT0_BTP		0x06
+#define MSHW0011_CMD_ADP1_PSR		0x07
+#define MSHW0011_CMD_BAT0_PSOC		0x09
+#define MSHW0011_CMD_BAT0_PMAX		0x0a
+#define MSHW0011_CMD_BAT0_PSRC		0x0b
+#define MSHW0011_CMD_BAT0_CHGI		0x0c
+#define MSHW0011_CMD_BAT0_ARTG		0x0d
+
+#define MSHW0011_NOTIFY_GET_VERSION	0x00
+#define MSHW0011_NOTIFY_ADP1		0x01
+#define MSHW0011_NOTIFY_BAT0_BST	0x02
+#define MSHW0011_NOTIFY_BAT0_BIX	0x05
+
+#define MSHW0011_ADP1_REG_PSR		0x04
+
+#define MSHW0011_BAT0_REG_CAPACITY		0x0c
+#define MSHW0011_BAT0_REG_FULL_CHG_CAPACITY	0x0e
+#define MSHW0011_BAT0_REG_DESIGN_CAPACITY	0x40
+#define MSHW0011_BAT0_REG_VOLTAGE	0x08
+#define MSHW0011_BAT0_REG_RATE		0x14
+#define MSHW0011_BAT0_REG_OEM		0x45
+#define MSHW0011_BAT0_REG_TYPE		0x4e
+#define MSHW0011_BAT0_REG_SERIAL_NO	0x56
+#define MSHW0011_BAT0_REG_CYCLE_CNT	0x6e
+
+#define MSHW0011_EV_2_5_MASK		GENMASK(8, 0)
+
+static const guid_t mshw0011_guid =
+	GUID_INIT(0x3F99E367, 0x6220, 0x4955, 0x8B, 0x0F, 0x06, 0xEF, 0x2A,
+		  0xE7, 0x94, 0x12);
+
+static int
+mshw0011_notify(struct mshw0011_data *cdata, u8 arg1, u8 arg2,
+		unsigned int *ret_value)
+{
+	union acpi_object *obj;
+	struct acpi_device *adev;
+	acpi_handle handle;
+	unsigned int i;
+
+	handle = ACPI_HANDLE(&cdata->adp1->dev);
+	if (!handle || acpi_bus_get_device(handle, &adev))
+		return -ENODEV;
+
+	obj = acpi_evaluate_dsm_typed(handle, &mshw0011_guid, arg1, arg2, NULL,
+				      ACPI_TYPE_BUFFER);
+	if (!obj) {
+		dev_err(&cdata->adp1->dev, "device _DSM execution failed\n");
+		return -ENODEV;
+	}
+
+	*ret_value = 0;
+	for (i = 0; i < obj->buffer.length; i++)
+		*ret_value |= obj->buffer.pointer[i] << (i * 8);
+
+	ACPI_FREE(obj);
+	return 0;
+}
+
+static const struct bix default_bix = {
+	.revision = 0x00,
+	.power_unit = 0x01,
+	.design_capacity = 0x1dca,
+	.last_full_charg_capacity = 0x1dca,
+	.battery_technology = 0x01,
+	.design_voltage = 0x10df,
+	.design_capacity_of_warning = 0x8f,
+	.design_capacity_of_low = 0x47,
+	.cycle_count = 0xffffffff,
+	.measurement_accuracy = 0x00015f90,
+	.max_sampling_time = 0x03e8,
+	.min_sampling_time = 0x03e8,
+	.max_average_interval = 0x03e8,
+	.min_average_interval = 0x03e8,
+	.battery_capacity_granularity_1 = 0x45,
+	.battery_capacity_granularity_2 = 0x11,
+	.model = "P11G8M",
+	.serial = "",
+	.type = "LION",
+	.OEM = "",
+};
+
+static int mshw0011_bix(struct mshw0011_data *cdata, struct bix *bix)
+{
+	struct i2c_client *client = cdata->bat0;
+	char buf[SURFACE_3_STRLEN];
+	int ret;
+
+	*bix = default_bix;
+
+	/* get design capacity */
+	ret = i2c_smbus_read_word_data(client,
+				       MSHW0011_BAT0_REG_DESIGN_CAPACITY);
+	if (ret < 0) {
+		dev_err(&client->dev, "Error reading design capacity: %d\n",
+			ret);
+		return ret;
+	}
+	bix->design_capacity = ret;
+
+	/* get last full charge capacity */
+	ret = i2c_smbus_read_word_data(client,
+				       MSHW0011_BAT0_REG_FULL_CHG_CAPACITY);
+	if (ret < 0) {
+		dev_err(&client->dev,
+			"Error reading last full charge capacity: %d\n", ret);
+		return ret;
+	}
+	bix->last_full_charg_capacity = ret;
+
+	/* get serial number */
+	ret = i2c_smbus_read_i2c_block_data(client, MSHW0011_BAT0_REG_SERIAL_NO,
+					    sizeof(buf), buf);
+	if (ret != sizeof(buf)) {
+		dev_err(&client->dev, "Error reading serial no: %d\n", ret);
+		return ret;
+	}
+	snprintf(bix->serial, ARRAY_SIZE(bix->serial), "%3pE%6pE", buf + 7, buf);
+
+	/* get cycle count */
+	ret = i2c_smbus_read_word_data(client, MSHW0011_BAT0_REG_CYCLE_CNT);
+	if (ret < 0) {
+		dev_err(&client->dev, "Error reading cycle count: %d\n", ret);
+		return ret;
+	}
+	bix->cycle_count = ret;
+
+	/* get OEM name */
+	ret = i2c_smbus_read_i2c_block_data(client, MSHW0011_BAT0_REG_OEM,
+					    4, buf);
+	if (ret != 4) {
+		dev_err(&client->dev, "Error reading cycle count: %d\n", ret);
+		return ret;
+	}
+	snprintf(bix->OEM, ARRAY_SIZE(bix->OEM), "%3pE", buf);
+
+	return 0;
+}
+
+static int mshw0011_bst(struct mshw0011_data *cdata, struct bst *bst)
+{
+	struct i2c_client *client = cdata->bat0;
+	int rate, capacity, voltage, state;
+	s16 tmp;
+
+	rate = i2c_smbus_read_word_data(client, MSHW0011_BAT0_REG_RATE);
+	if (rate < 0)
+		return rate;
+
+	capacity = i2c_smbus_read_word_data(client, MSHW0011_BAT0_REG_CAPACITY);
+	if (capacity < 0)
+		return capacity;
+
+	voltage = i2c_smbus_read_word_data(client, MSHW0011_BAT0_REG_VOLTAGE);
+	if (voltage < 0)
+		return voltage;
+
+	tmp = rate;
+	bst->battery_present_rate = abs((s32)tmp);
+
+	state = 0;
+	if ((s32) tmp > 0)
+		state |= ACPI_BATTERY_STATE_CHARGING;
+	else if ((s32) tmp < 0)
+		state |= ACPI_BATTERY_STATE_DISCHARGING;
+	bst->battery_state = state;
+
+	bst->battery_remaining_capacity = capacity;
+	bst->battery_present_voltage = voltage;
+
+	return 0;
+}
+
+static int mshw0011_adp_psr(struct mshw0011_data *cdata)
+{
+	struct i2c_client *client = cdata->adp1;
+	int ret;
+
+	ret = i2c_smbus_read_byte_data(client, MSHW0011_ADP1_REG_PSR);
+	if (ret < 0)
+		return ret;
+
+	return ret;
+}
+
+static int mshw0011_isr(struct mshw0011_data *cdata)
+{
+	struct bst bst;
+	struct bix bix;
+	int ret;
+	bool status, bat_status;
+
+	ret = mshw0011_adp_psr(cdata);
+	if (ret < 0)
+		return ret;
+
+	status = ret;
+	if (status != cdata->charging)
+		mshw0011_notify(cdata, cdata->notify_mask,
+				MSHW0011_NOTIFY_ADP1, &ret);
+
+	cdata->charging = status;
+
+	ret = mshw0011_bst(cdata, &bst);
+	if (ret < 0)
+		return ret;
+
+	bat_status = bst.battery_state;
+	if (bat_status != cdata->bat_charging)
+		mshw0011_notify(cdata, cdata->notify_mask,
+				MSHW0011_NOTIFY_BAT0_BST, &ret);
+
+	cdata->bat_charging = bat_status;
+
+	ret = mshw0011_bix(cdata, &bix);
+	if (ret < 0)
+		return ret;
+
+	if (bix.last_full_charg_capacity != cdata->full_capacity)
+		mshw0011_notify(cdata, cdata->notify_mask,
+				MSHW0011_NOTIFY_BAT0_BIX, &ret);
+
+	cdata->full_capacity = bix.last_full_charg_capacity;
+
+	return 0;
+}
+
+static int mshw0011_poll_task(void *data)
+{
+	struct mshw0011_data *cdata = data;
+	int ret = 0;
+
+	cdata->kthread_running = true;
+
+	set_freezable();
+
+	while (!kthread_should_stop()) {
+		schedule_timeout_interruptible(POLL_INTERVAL);
+		try_to_freeze();
+		ret = mshw0011_isr(data);
+		if (ret)
+			break;
+	}
+
+	cdata->kthread_running = false;
+	return ret;
+}
+
+static acpi_status
+mshw0011_space_handler(u32 function, acpi_physical_address command,
+			u32 bits, u64 *value64,
+			void *handler_context, void *region_context)
+{
+	struct gsb_buffer *gsb = (struct gsb_buffer *)value64;
+	struct mshw0011_handler_data *data = handler_context;
+	struct acpi_connection_info *info = &data->info;
+	struct acpi_resource_i2c_serialbus *sb;
+	struct i2c_client *client = data->client;
+	struct mshw0011_data *cdata = i2c_get_clientdata(client);
+	struct acpi_resource *ares;
+	u32 accessor_type = function >> 16;
+	acpi_status ret;
+	int status = 1;
+
+	ret = acpi_buffer_to_resource(info->connection, info->length, &ares);
+	if (ACPI_FAILURE(ret))
+		return ret;
+
+	if (!value64 || ares->type != ACPI_RESOURCE_TYPE_SERIAL_BUS) {
+		ret = AE_BAD_PARAMETER;
+		goto err;
+	}
+
+	sb = &ares->data.i2c_serial_bus;
+	if (sb->type != ACPI_RESOURCE_SERIAL_TYPE_I2C) {
+		ret = AE_BAD_PARAMETER;
+		goto err;
+	}
+
+	if (accessor_type != ACPI_GSB_ACCESS_ATTRIB_RAW_PROCESS) {
+		ret = AE_BAD_PARAMETER;
+		goto err;
+	}
+
+	if (gsb->cmd.arg0 == MSHW0011_CMD_DEST_ADP1 &&
+	    gsb->cmd.arg1 == MSHW0011_CMD_ADP1_PSR) {
+		ret = mshw0011_adp_psr(cdata);
+		if (ret >= 0) {
+			status = ret;
+			ret = 0;
+		}
+		goto out;
+	}
+
+	if (gsb->cmd.arg0 != MSHW0011_CMD_DEST_BAT0) {
+		ret = AE_BAD_PARAMETER;
+		goto err;
+	}
+
+	switch (gsb->cmd.arg1) {
+	case MSHW0011_CMD_BAT0_STA:
+		break;
+	case MSHW0011_CMD_BAT0_BIX:
+		ret = mshw0011_bix(cdata, &gsb->bix);
+		break;
+	case MSHW0011_CMD_BAT0_BTP:
+		cdata->trip_point = gsb->cmd.arg2;
+		break;
+	case MSHW0011_CMD_BAT0_BST:
+		ret = mshw0011_bst(cdata, &gsb->bst);
+		break;
+	default:
+		pr_info("command(0x%02x) is not supported.\n", gsb->cmd.arg1);
+		ret = AE_BAD_PARAMETER;
+		goto err;
+	}
+
+ out:
+	gsb->ret = status;
+	gsb->status = 0;
+
+ err:
+	ACPI_FREE(ares);
+	return ret;
+}
+
+static int mshw0011_install_space_handler(struct i2c_client *client)
+{
+	acpi_handle handle;
+	struct mshw0011_handler_data *data;
+	acpi_status status;
+
+	handle = ACPI_HANDLE(&client->dev);
+	if (!handle)
+		return -ENODEV;
+
+	data = kzalloc(sizeof(struct mshw0011_handler_data),
+			    GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->client = client;
+	status = acpi_bus_attach_private_data(handle, (void *)data);
+	if (ACPI_FAILURE(status)) {
+		kfree(data);
+		return -ENOMEM;
+	}
+
+	status = acpi_install_address_space_handler(handle,
+				ACPI_ADR_SPACE_GSBUS,
+				&mshw0011_space_handler,
+				NULL,
+				data);
+	if (ACPI_FAILURE(status)) {
+		dev_err(&client->dev, "Error installing i2c space handler\n");
+		acpi_bus_detach_private_data(handle);
+		kfree(data);
+		return -ENOMEM;
+	}
+
+	acpi_walk_dep_device_list(handle);
+	return 0;
+}
+
+static void mshw0011_remove_space_handler(struct i2c_client *client)
+{
+	struct mshw0011_handler_data *data;
+	acpi_handle handle;
+	acpi_status status;
+
+	handle = ACPI_HANDLE(&client->dev);
+	if (!handle)
+		return;
+
+	acpi_remove_address_space_handler(handle,
+				ACPI_ADR_SPACE_GSBUS,
+				&mshw0011_space_handler);
+
+	status = acpi_bus_get_private_data(handle, (void **)&data);
+	if (ACPI_SUCCESS(status))
+		kfree(data);
+
+	acpi_bus_detach_private_data(handle);
+}
+
+static int mshw0011_probe(struct i2c_client *client)
+{
+	struct i2c_board_info board_info;
+	struct device *dev = &client->dev;
+	struct i2c_client *bat0;
+	struct mshw0011_data *data;
+	int error, mask;
+
+	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->adp1 = client;
+	i2c_set_clientdata(client, data);
+
+	memset(&board_info, 0, sizeof(board_info));
+	strlcpy(board_info.type, "MSHW0011-bat0", I2C_NAME_SIZE);
+
+	bat0 = i2c_acpi_new_device(dev, 1, &board_info);
+	if (!bat0)
+		return -ENOMEM;
+
+	data->bat0 = bat0;
+	i2c_set_clientdata(bat0, data);
+
+	error = mshw0011_notify(data, 1, MSHW0011_NOTIFY_GET_VERSION, &mask);
+	if (error)
+		goto out_err;
+
+	data->notify_mask = mask == MSHW0011_EV_2_5_MASK;
+
+	data->poll_task = kthread_run(mshw0011_poll_task, data, "mshw0011_adp");
+	if (IS_ERR(data->poll_task)) {
+		error = PTR_ERR(data->poll_task);
+		dev_err(&client->dev, "Unable to run kthread err %d\n", error);
+		goto out_err;
+	}
+
+	error = mshw0011_install_space_handler(client);
+	if (error)
+		goto out_err;
+
+	return 0;
+
+out_err:
+	if (data->kthread_running)
+		kthread_stop(data->poll_task);
+	i2c_unregister_device(data->bat0);
+	return error;
+}
+
+static int mshw0011_remove(struct i2c_client *client)
+{
+	struct mshw0011_data *cdata = i2c_get_clientdata(client);
+
+	mshw0011_remove_space_handler(client);
+
+	if (cdata->kthread_running)
+		kthread_stop(cdata->poll_task);
+
+	i2c_unregister_device(cdata->bat0);
+
+	return 0;
+}
+
+static const struct acpi_device_id mshw0011_acpi_match[] = {
+	{ "MSHW0011", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(acpi, mshw0011_acpi_match);
+
+static struct i2c_driver mshw0011_driver = {
+	.probe_new = mshw0011_probe,
+	.remove = mshw0011_remove,
+	.driver = {
+		.name = "mshw0011",
+		.acpi_match_table = ACPI_PTR(mshw0011_acpi_match),
+	},
+};
+module_i2c_driver(mshw0011_driver);
+
+MODULE_AUTHOR("Benjamin Tissoires <benjamin.tissoires@gmail.com>");
+MODULE_DESCRIPTION("mshw0011 driver");
+MODULE_LICENSE("GPL v2");