[PATCH 7/9] I2C/ACPI: Add i2c ACPI operation region support

[Lan Tianyu <tianyu.lan@intel.com>]

ACPI 5.0 spec(5.5.2.4.5) defines GenericSerialBus(i2c, spi, uart) operation region.
It allows ACPI aml code able to access such kind of devices to implement
some ACPI standard method.

ACPI Spec defines some access attribute to associate with i2c protocol.
AttribQuick 	       	       		Read/Write Quick Protocol
AttribSendReceive			Send/Receive Byte Protocol
AttribByte 			 	Read/Write Byte Protocol
AttribWord				Read/Write Word Protocol
AttribBlock				Read/Write Block Protocol
AttribBytes				Read/Write N-Bytes Protocol
AttribProcessCall			Process Call Protocol
AttribBlockProcessCall			Write Block-Read Block Process Call Protocol
AttribRawBytes 				Raw Read/Write N-BytesProtocol
AttribRawProcessBytes			Raw Process Call Protocol

On the Asus T100TA, Bios use GenericSerialBus operation region to access
i2c device to get battery info.

Sample code From Asus T100TA

    Scope (_SB.I2C1)
    {
        Name (UMPC, ResourceTemplate ()
        {
            I2cSerialBus (0x0066, ControllerInitiated, 0x00061A80,
                AddressingMode7Bit, "\\_SB.I2C1",
                0x00, ResourceConsumer, ,
                )
        })

	...

        OperationRegion (DVUM, GenericSerialBus, Zero, 0x0100)
        Field (DVUM, BufferAcc, NoLock, Preserve)
        {
            Connection (UMPC),
            Offset (0x81),
            AccessAs (BufferAcc, AttribBytes (0x3E)),
            FGC0,   8
        }
	...
     }

     Device (BATC)
     {
         Name (_HID, EisaId ("PNP0C0A"))  // _HID: Hardware ID
         Name (_UID, One)  // _UID: Unique ID
	 ...

            Method (_BST, 0, NotSerialized)  // _BST: Battery Status
            {
                If (LEqual (AVBL, One))
                {
                    Store (FGC0, BFFG)
                    If (LNotEqual (STAT, One))
                    {
                        ShiftRight (CHST, 0x04, Local0)
                        And (Local0, 0x03, Local0)
                        If (LOr (LEqual (Local0, One), LEqual (Local0, 0x02)))
                        {
                            Store (0x02, Local1)
                        }
	...

    }

The i2c operation region is defined under I2C1 scope. _BST method under
battery device BATC read battery status from the field "FCG0". The request
would be sent to i2c operation region handler.

This patch is to add i2c ACPI operation region support. Due to there are
only "Byte" and "N-Bytes" protocol access on the Asus T100TA, other protocols
have not been tested.

About RawBytes and RawProcessBytes protocol, they needs specific drivers to interpret
reference data from AML code according ACPI 5.0 SPEC(5.5.2.4.5.3.9 and 5.5.2.4.5.3.10).
So far, not found such case and will add when find real case.

Signed-off-by: Lan Tianyu <tianyu.lan@intel.com>
---
 drivers/i2c/Makefile   |   5 +-
 drivers/i2c/i2c-acpi.c | 282 +++++++++++++++++++++++++++++++++++++++++++++++++
 drivers/i2c/i2c-core.c |   2 +
 include/linux/acpi.h   |  11 ++
 include/linux/i2c.h    |  10 ++
 5 files changed, 309 insertions(+), 1 deletion(-)
 create mode 100644 drivers/i2c/i2c-acpi.c

diff --git a/drivers/i2c/Makefile b/drivers/i2c/Makefile
index 1722f50..80db307 100644
--- a/drivers/i2c/Makefile
+++ b/drivers/i2c/Makefile
@@ -2,8 +2,11 @@
 # Makefile for the i2c core.
 #
 
+i2ccore-y := i2c-core.o
+i2ccore-$(CONFIG_ACPI)		+= i2c-acpi.o
+
 obj-$(CONFIG_I2C_BOARDINFO)	+= i2c-boardinfo.o
-obj-$(CONFIG_I2C)		+= i2c-core.o
+obj-$(CONFIG_I2C)		+= i2ccore.o
 obj-$(CONFIG_I2C_SMBUS)		+= i2c-smbus.o
 obj-$(CONFIG_I2C_CHARDEV)	+= i2c-dev.o
 obj-$(CONFIG_I2C_MUX)		+= i2c-mux.o
diff --git a/drivers/i2c/i2c-acpi.c b/drivers/i2c/i2c-acpi.c
new file mode 100644
index 0000000..942abdf
--- /dev/null
+++ b/drivers/i2c/i2c-acpi.c
@@ -0,0 +1,282 @@
+/*
+ * I2C ACPI code
+ *
+ * Copyright (C) 2014 Intel Corp
+ *
+ * Author: Lan Tianyu <tianyu.lan@intel.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that 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.
+ */
+#define pr_fmt(fmt) "I2C/ACPI : " fmt
+
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/acpi.h>
+
+struct acpi_i2c_handler_data {
+	struct acpi_connection_info info;
+	struct i2c_adapter *adapter;
+} __packed;
+
+struct gsb_buffer {
+	u8	status;
+	u8	len;
+	union {
+		u16	wdata;
+		u8	bdata;
+		u8	data[0];
+	};
+} __packed;
+
+static int acpi_gsb_i2c_read_bytes(struct i2c_client *client,
+		u8 cmd, u8 *data, u8 data_len)
+{
+
+	struct i2c_msg msgs[2];
+	int ret;
+	u8  *buffer;
+
+	buffer = kzalloc(data_len, GFP_KERNEL);
+	if (!buffer)
+		return AE_NO_MEMORY;
+
+	msgs[0].addr = client->addr;
+	msgs[0].flags = client->flags;
+	msgs[0].len = 1;
+	msgs[0].buf = &cmd;
+
+	msgs[1].addr = client->addr;
+	msgs[1].flags = client->flags | I2C_M_RD;
+	msgs[1].len = data_len;
+	msgs[1].buf = buffer;
+
+	ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
+	if (ret < 0)
+		pr_err("i2c read failed\n");
+	else
+		memcpy(data, buffer, data_len);
+
+	kfree(buffer);
+	return ret;
+}
+
+static int acpi_gsb_i2c_write_bytes(struct i2c_client *client,
+		u8 cmd, u8 *data, u8 data_len)
+{
+
+	struct i2c_msg msgs[1];
+	u8  *buffer;
+	int ret = AE_OK;
+
+	buffer = kzalloc(data_len + 1, GFP_KERNEL);
+	if (!buffer)
+		return AE_NO_MEMORY;
+
+	buffer[0] = cmd;
+	memcpy(buffer + 1, data, data_len);
+
+	msgs[0].addr = client->addr;
+	msgs[0].flags = client->flags;
+	msgs[0].len = data_len + 1;
+	msgs[0].buf = buffer;
+
+	ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
+	if (ret < 0)
+		pr_err("i2c write failed\n");
+
+	kfree(buffer);
+	return ret;
+}
+
+static acpi_status
+acpi_i2c_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 acpi_i2c_handler_data *data = handler_context;
+	struct acpi_connection_info *info = &data->info;
+	struct acpi_resource_i2c_serialbus *sb;
+	struct i2c_adapter *adapter = data->adapter;
+	struct i2c_client client;
+	struct acpi_resource *ares;
+	u32 accessor_type = function >> 16;
+	u8 action = function & ACPI_IO_MASK;
+	int status;
+
+	acpi_buffer_to_resource(info->connection, info->length, &ares);
+	if (!value64 || ares->type != ACPI_RESOURCE_TYPE_SERIAL_BUS)
+		return AE_BAD_PARAMETER;
+
+	sb = &ares->data.i2c_serial_bus;
+	if (sb->type != ACPI_RESOURCE_SERIAL_TYPE_I2C)
+		return AE_BAD_PARAMETER;
+
+	client.adapter = adapter;
+	client.addr = sb->slave_address;
+	client.flags = 0;
+
+	if (sb->access_mode == ACPI_I2C_10BIT_MODE)
+		client.flags |= I2C_CLIENT_TEN;
+
+	switch (accessor_type) {
+	case ACPI_GSB_ACCESS_ATTRIB_QUICK:
+		if (action == ACPI_READ)
+			status = i2c_smbus_quick_read(&client);
+		else
+			status = i2c_smbus_quick_write(&client);
+		break;
+
+	case ACPI_GSB_ACCESS_ATTRIB_SEND_RCV:
+		if (action == ACPI_READ) {
+			status = i2c_smbus_read_byte(&client);
+			if (status >= 0) {
+				gsb->bdata = status;
+				status = 0;
+			}
+		} else {
+			status = i2c_smbus_write_byte(&client, gsb->bdata);
+		}
+		break;
+
+	case ACPI_GSB_ACCESS_ATTRIB_BYTE:
+		if (action == ACPI_READ) {
+			status = i2c_smbus_read_byte_data(&client, command);
+			if (status >= 0) {
+				gsb->bdata = status;
+				status = 0;
+			}
+		} else {
+			status = i2c_smbus_write_byte_data(&client, command,
+					gsb->bdata);
+		}
+		break;
+
+	case ACPI_GSB_ACCESS_ATTRIB_WORD:
+		if (action == ACPI_READ) {
+			status = i2c_smbus_read_word_data(&client, command);
+			if (status >= 0) {
+				gsb->wdata = status;
+				status = 0;
+			}
+		} else {
+			status = i2c_smbus_write_word_data(&client, command,
+					gsb->wdata);
+		}
+		break;
+
+	case ACPI_GSB_ACCESS_ATTRIB_BLOCK:
+		if (action == ACPI_READ) {
+			status = i2c_smbus_read_block_data(&client, command,
+					gsb->data);
+			if (status >= 0) {
+				gsb->len = status;
+				status = 0;
+			}
+		} else {
+			status = i2c_smbus_write_block_data(&client, command,
+					gsb->len, gsb->data);
+		}
+		break;
+
+	case ACPI_GSB_ACCESS_ATTRIB_MULTIBYTE:
+		if (action == ACPI_READ) {
+			status = acpi_gsb_i2c_read_bytes(&client, command,
+					gsb->data, info->access_length);
+			if (status > 0)
+				status = 0;
+		} else {
+			status = acpi_gsb_i2c_write_bytes(&client, command,
+					gsb->data, info->access_length);
+		}
+		break;
+
+	case ACPI_GSB_ACCESS_ATTRIB_WORD_CALL:
+		status = i2c_smbus_word_proc_call(&client, command, gsb->wdata);
+		if (status >= 0) {
+			gsb->wdata = status;
+			status = 0;
+		}
+		break;
+
+	case ACPI_GSB_ACCESS_ATTRIB_BLOCK_CALL:
+		status = i2c_smbus_block_proc_call(&client, command, gsb->len,
+				gsb->data);
+		if (status > 0) {
+			gsb->len = status;
+			status = 0;
+		}
+		break;
+
+	default:
+		pr_info("protocl(0x%02x) is not supported.\n", accessor_type);
+		return AE_BAD_PARAMETER;
+	}
+
+	gsb->status = status;
+	return AE_OK;
+}
+
+
+int acpi_i2c_install_space_handler(struct i2c_adapter *adapter)
+{
+	acpi_handle handle = ACPI_HANDLE(adapter->dev.parent);
+	struct acpi_i2c_handler_data *data;
+	acpi_status status;
+
+	if (!handle)
+		return -ENODEV;
+
+	data = kzalloc(sizeof(struct acpi_i2c_handler_data),
+			    GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->adapter = adapter;
+	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,
+				&acpi_i2c_space_handler,
+				NULL,
+				data);
+	if (ACPI_FAILURE(status)) {
+		pr_err("Error installing i2c space handler\n");
+		acpi_bus_attach_private_data(handle, NULL);
+		kfree(data);
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
+void acpi_i2c_remove_space_handler(struct i2c_adapter *adapter)
+{
+	acpi_handle handle = ACPI_HANDLE(adapter->dev.parent);
+	struct acpi_i2c_handler_data *data;
+	acpi_status status;
+
+	if (!handle)
+		return;
+
+	acpi_remove_address_space_handler(handle,
+				ACPI_ADR_SPACE_GSBUS,
+				&acpi_i2c_space_handler);
+
+	status = acpi_bus_get_private_data(handle, (void **)&data);
+	if (ACPI_SUCCESS(status))
+		kfree(data);
+}
diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index 638befd..bb9dc56 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -1293,6 +1293,7 @@ exit_recovery:
 	/* create pre-declared device nodes */
 	of_i2c_register_devices(adap);
 	acpi_i2c_register_devices(adap);
+	acpi_i2c_install_space_handler(adap);
 
 	if (adap->nr < __i2c_first_dynamic_bus_num)
 		i2c_scan_static_board_info(adap);
@@ -1466,6 +1467,7 @@ void i2c_del_adapter(struct i2c_adapter *adap)
 		return;
 	}
 
+	acpi_i2c_remove_space_handler(adap);
 	/* Tell drivers about this removal */
 	mutex_lock(&core_lock);
 	bus_for_each_drv(&i2c_bus_type, NULL, adap,
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index 7a8f2cd..ea53b9b 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -361,6 +361,17 @@ extern bool osc_sb_apei_support_acked;
 #define OSC_PCI_EXPRESS_CAPABILITY_CONTROL	0x00000010
 #define OSC_PCI_CONTROL_MASKS			0x0000001f
 
+#define ACPI_GSB_ACCESS_ATTRIB_QUICK		0x00000002
+#define ACPI_GSB_ACCESS_ATTRIB_SEND_RCV         0x00000004
+#define ACPI_GSB_ACCESS_ATTRIB_BYTE		0x00000006
+#define ACPI_GSB_ACCESS_ATTRIB_WORD		0x00000008
+#define ACPI_GSB_ACCESS_ATTRIB_BLOCK		0x0000000A
+#define ACPI_GSB_ACCESS_ATTRIB_MULTIBYTE	0x0000000B
+#define ACPI_GSB_ACCESS_ATTRIB_WORD_CALL	0x0000000C
+#define ACPI_GSB_ACCESS_ATTRIB_BLOCK_CALL	0x0000000D
+#define ACPI_GSB_ACCESS_ATTRIB_RAW_BYTES	0x0000000E
+#define ACPI_GSB_ACCESS_ATTRIB_RAW_PROCESS	0x0000000F
+
 extern acpi_status acpi_pci_osc_control_set(acpi_handle handle,
 					     u32 *mask, u32 req);
 
diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index 724440a..681e689 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -583,4 +583,14 @@ static inline struct i2c_adapter *of_find_i2c_adapter_by_node(struct device_node
 }
 #endif /* CONFIG_OF */
 
+#ifdef CONFIG_ACPI
+int acpi_i2c_install_space_handler(struct i2c_adapter *adapter);
+void acpi_i2c_remove_space_handler(struct i2c_adapter *adapter);
+#else
+static inline void acpi_i2c_remove_space_handler(struct i2c_adapter *adapter)
+{ }
+static inline int acpi_i2c_install_space_handler(struct i2c_adapter *adapter)
+{ return 0; }
+#endif
+
 #endif /* _LINUX_I2C_H */
-- 
1.8.4.rc0.1.g8f6a3e5.dirty