iio: imu: inv_mpu6050: Create mux clients for ACPI

This is a follow up patches after adding i2c mux adapter for bypass
mode. Potentially many different types of sensor can be attached to
INVMPU6XXX device, which can be connected to main cpu i2c bus in
bypass mode.
Why do we need this?
The system ACPI table entry will consist of only one device for
INV6XXX, assuming that this driver will handle all connected sensors.
That is not true for the Linux driver. There are bunch of IIO drivers
for each sensors, hence we created a mux on this device. So to load
these additional drivers, we need to create i2c devices for them
in this driver using this mux adapter.

There are multiple options:
1. Use the auto detect feature, this needs a new i2c class for the
adapter as the existing HWMON class is not acceptable. Also the
autodetect has overhead of executing detect method for each
matching class of adapters.
This is a simple implementation. This option was previously submitted
with not a happy feedback.

2. Option is use ACPI magic and parse the configuration data. What
we need to create a i2c device at a minimum is address and a name.
Address can be obtained for secondary device in more or less in a
standard way from using _CRS element. But there is no name. To get
name we need to process proprietary vendor data. Not having name is
not fun, as you have to create device using the device name of
INVN6XXXX, respecting driver duplicate name space restriction.
Also each client driver needs to have this name in the id table.
Since multiple driver can be loaded, the driver should be able to
detect its presence and gracefully exit for the other client driver
to take it over.
So we use two step process:
- Use DMI to id platform and parse propritery data. This is not uncommon
for many x86 platform specific driver. We will get both name and address.
The change created necessary infrastructure to add more properitery vendor
data parsing.
- If DMI match fails, then create device on INV6XXX-client (we can't
create with same name as INV6XXX as it will cause duplicate name and driver
model will reject.) With this each client sensor driver which needs to get
attached via INV6XXXX, need this name in the id table and detect the
physical presence of sensor in probe and exit if not found.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/imu/inv_mpu6050/Makefile

@@ -3,4 +3,4 @@
 #
 
 obj-$(CONFIG_INV_MPU6050_IIO) += inv-mpu6050.o
-inv-mpu6050-objs := inv_mpu_core.o inv_mpu_ring.o inv_mpu_trigger.o
+inv-mpu6050-objs := inv_mpu_core.o inv_mpu_ring.o inv_mpu_trigger.o inv_mpu_acpi.o

drivers/iio/imu/inv_mpu6050/inv_mpu_acpi.c

@@ -0,0 +1,211 @@
+/*
+ * inv_mpu_acpi: ACPI processing for creating client devices
+ * Copyright (c) 2015, Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ */
+
+#ifdef CONFIG_ACPI
+
+#include <linux/kernel.h>
+#include <linux/i2c.h>
+#include <linux/dmi.h>
+#include <linux/acpi.h>
+#include "inv_mpu_iio.h"
+
+enum inv_mpu_product_name {
+	INV_MPU_NOT_MATCHED,
+	INV_MPU_ASUS_T100TA,
+};
+
+static enum inv_mpu_product_name matched_product_name;
+
+static int __init asus_t100_matched(const struct dmi_system_id *d)
+{
+	matched_product_name = INV_MPU_ASUS_T100TA;
+
+	return 0;
+}
+
+static const struct dmi_system_id inv_mpu_dev_list[] = {
+	{
+	.callback = asus_t100_matched,
+	.ident = "Asus Transformer Book T100",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "T100TA"),
+			DMI_MATCH(DMI_PRODUCT_VERSION, "1.0"),
+		},
+	},
+	/* Add more matching tables here..*/
+	{}
+};
+
+static int asus_acpi_get_sensor_info(struct acpi_device *adev,
+				     struct i2c_client *client,
+				     struct i2c_board_info *info)
+{
+	struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
+	int i;
+	acpi_status status;
+	union acpi_object *cpm;
+
+	status = acpi_evaluate_object(adev->handle, "CNF0", NULL, &buffer);
+	if (ACPI_FAILURE(status))
+		return -ENODEV;
+
+	cpm = buffer.pointer;
+	for (i = 0; i < cpm->package.count; ++i) {
+		union acpi_object *elem;
+		int j;
+
+		elem = &(cpm->package.elements[i]);
+		for (j = 0; j < elem->package.count; ++j) {
+			union acpi_object *sub_elem;
+
+			sub_elem = &(elem->package.elements[j]);
+			if (sub_elem->type == ACPI_TYPE_STRING)
+				strlcpy(info->type, sub_elem->string.pointer,
+					sizeof(info->type));
+			else if (sub_elem->type == ACPI_TYPE_INTEGER) {
+				if (sub_elem->integer.value != client->addr) {
+					info->addr = sub_elem->integer.value;
+					break; /* Not a MPU6500 primary */
+				}
+			}
+		}
+	}
+
+	kfree(buffer.pointer);
+
+	return cpm->package.count;
+}
+
+static int acpi_i2c_check_resource(struct acpi_resource *ares, void *data)
+{
+	u32 *addr = data;
+
+	if (ares->type == ACPI_RESOURCE_TYPE_SERIAL_BUS) {
+		struct acpi_resource_i2c_serialbus *sb;
+
+		sb = &ares->data.i2c_serial_bus;
+		if (sb->type == ACPI_RESOURCE_SERIAL_TYPE_I2C) {
+			if (*addr)
+				*addr |= (sb->slave_address << 16);
+			else
+				*addr = sb->slave_address;
+		}
+	}
+
+	/* Tell the ACPI core that we already copied this address */
+	return 1;
+}
+
+static int inv_mpu_process_acpi_config(struct i2c_client *client,
+				       unsigned short *primary_addr,
+				       unsigned short *secondary_addr)
+{
+	const struct acpi_device_id *id;
+	struct acpi_device *adev;
+	u32 i2c_addr = 0;
+	LIST_HEAD(resources);
+	int ret;
+
+	id = acpi_match_device(client->dev.driver->acpi_match_table,
+			       &client->dev);
+	if (!id)
+		return -ENODEV;
+
+	adev = ACPI_COMPANION(&client->dev);
+	if (!adev)
+		return -ENODEV;
+
+	ret = acpi_dev_get_resources(adev, &resources,
+				     acpi_i2c_check_resource, &i2c_addr);
+	if (ret < 0)
+		return ret;
+
+	acpi_dev_free_resource_list(&resources);
+	*primary_addr = i2c_addr & 0x0000ffff;
+	*secondary_addr = (i2c_addr & 0xffff0000) >> 16;
+
+	return 0;
+}
+
+int inv_mpu_acpi_create_mux_client(struct inv_mpu6050_state *st)
+{
+
+	st->mux_client = NULL;
+	if (ACPI_HANDLE(&st->client->dev)) {
+		struct i2c_board_info info;
+		struct acpi_device *adev;
+		int ret = -1;
+
+		adev = ACPI_COMPANION(&st->client->dev);
+		memset(&info, 0, sizeof(info));
+
+		dmi_check_system(inv_mpu_dev_list);
+		switch (matched_product_name) {
+		case INV_MPU_ASUS_T100TA:
+			ret = asus_acpi_get_sensor_info(adev, st->client,
+							&info);
+			break;
+		/* Add more matched product processing here */
+		default:
+			break;
+		}
+
+		if (ret < 0) {
+			/* No matching DMI, so create device on INV6XX type */
+			unsigned short primary, secondary;
+
+			ret = inv_mpu_process_acpi_config(st->client, &primary,
+							  &secondary);
+			if (!ret && secondary) {
+				char *name;
+
+				info.addr = secondary;
+				strlcpy(info.type, dev_name(&adev->dev),
+					sizeof(info.type));
+				name = strchr(info.type, ':');
+				if (name)
+					*name = '\0';
+				strlcat(info.type, "-client",
+					sizeof(info.type));
+			} else
+				return 0; /* no secondary addr, which is OK */
+		}
+		st->mux_client = i2c_new_device(st->mux_adapter, &info);
+		if (!st->mux_client)
+			return -ENODEV;
+
+	}
+
+	return 0;
+}
+
+void inv_mpu_acpi_delete_mux_client(struct inv_mpu6050_state *st)
+{
+	if (st->mux_client)
+		i2c_unregister_device(st->mux_client);
+}
+#else
+
+#include "inv_mpu_iio.h"
+
+int inv_mpu_acpi_create_mux_client(struct inv_mpu6050_state *st)
+{
+	return 0;
+}
+
+void inv_mpu_acpi_delete_mux_client(struct inv_mpu6050_state *st)
+{
+}
+#endif

drivers/iio/imu/inv_mpu6050/inv_mpu_core.c

@@ -821,8 +821,14 @@ static int inv_mpu_probe(struct i2c_client *client,
 		goto out_unreg_device;
 	}
 
+	result = inv_mpu_acpi_create_mux_client(st);
+	if (result)
+		goto out_del_mux;
+
 	return 0;
 
+out_del_mux:
+	i2c_del_mux_adapter(st->mux_adapter);
 out_unreg_device:
 	iio_device_unregister(indio_dev);
 out_remove_trigger:
@@ -837,6 +843,7 @@ static int inv_mpu_remove(struct i2c_client *client)
 	struct iio_dev *indio_dev = i2c_get_clientdata(client);
 	struct inv_mpu6050_state *st = iio_priv(indio_dev);
 
+	inv_mpu_acpi_delete_mux_client(st);
 	i2c_del_mux_adapter(st->mux_adapter);
 	iio_device_unregister(indio_dev);
 	inv_mpu6050_remove_trigger(st);

drivers/iio/imu/inv_mpu6050/inv_mpu_iio.h

@@ -121,6 +121,7 @@ struct inv_mpu6050_state {
 	spinlock_t time_stamp_lock;
 	struct i2c_client *client;
 	struct i2c_adapter *mux_adapter;
+	struct i2c_client *mux_client;
 	unsigned int powerup_count;
 	struct inv_mpu6050_platform_data plat_data;
 	DECLARE_KFIFO(timestamps, long long, TIMESTAMP_FIFO_SIZE);
@@ -251,3 +252,5 @@ int inv_reset_fifo(struct iio_dev *indio_dev);
 int inv_mpu6050_switch_engine(struct inv_mpu6050_state *st, bool en, u32 mask);
 int inv_mpu6050_write_reg(struct inv_mpu6050_state *st, int reg, u8 val);
 int inv_mpu6050_set_power_itg(struct inv_mpu6050_state *st, bool power_on);
+int inv_mpu_acpi_create_mux_client(struct inv_mpu6050_state *st);
+void inv_mpu_acpi_delete_mux_client(struct inv_mpu6050_state *st);