southbridge/intel/common: Add Process Call

Add functionality to use process call cycle. It can be used to
write/read data to/from e.g. EEPROM attached to SMBus Controller
via I2C.

Tested on:
* C246

Change-Id: Ifdac6cf70a4ce744601f5d152a83d2125ea88360
Signed-off-by: Christian Walter <christian.walter@9elements.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/39875
Reviewed-by: Patrick Rudolph <siro@das-labor.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

2 files changed, 38 insertions, 0 deletions

diff --git a/src/include/device/smbus_host.h b/src/include/device/smbus_host.h
index 6e6163f062..d9390eaf2d 100644
--- a/src/include/device/smbus_host.h
+++ b/src/include/device/smbus_host.h
@@ -17,6 +17,7 @@ int do_smbus_write_word(uintptr_t base, u8 device, u8 address, u16 data);
 
 int do_smbus_block_read(uintptr_t base, u8 device, u8 cmd, size_t max_bytes, u8 *buf);
 int do_smbus_block_write(uintptr_t base, u8 device, u8 cmd, size_t bytes, const u8 *buf);
+int do_smbus_process_call(uintptr_t base, u8 device, u8 cmd, u16 data, u16 *buf);
 
 /* For Intel, implemented since ICH5. */
 int do_i2c_eeprom_read(uintptr_t base, u8 device, u8 offset, size_t bytes, u8 *buf);
diff --git a/src/southbridge/intel/common/smbus.c b/src/southbridge/intel/common/smbus.c
index 95c2fd0957..8b19b7d900 100644
--- a/src/southbridge/intel/common/smbus.c
+++ b/src/southbridge/intel/common/smbus.c
@@ -33,6 +33,7 @@
 #define I801_BYTE		(1 << 2)
 #define I801_BYTE_DATA		(2 << 2)
 #define I801_WORD_DATA		(3 << 2)
+#define I801_PROCESS_CALL	(4 << 2)
 #define I801_BLOCK_DATA		(5 << 2)
 #define I801_I2C_BLOCK_DATA	(6 << 2) /* ICH5 and later */
 
@@ -391,6 +392,42 @@ int do_smbus_block_read(uintptr_t base, u8 device, u8 cmd, size_t max_bytes, u8
 	return ret;
 }
 
+/*
+ * The caller is responsible of settings HOSTC I2C_EN bit prior to making this
+ * call!
+ */
+int do_smbus_process_call(uintptr_t base, u8 device, u8 cmd, u16 data, u16 *buf)
+{
+	int ret;
+
+	/* Set up for process call */
+	ret = setup_command(base, I801_PROCESS_CALL, XMIT_WRITE(device));
+	if (ret < 0)
+		return ret;
+
+	/* cmd will only be send if I2C_EN is zero */
+	host_outb(base, SMBHSTCMD, cmd);
+
+	host_outb(base, SMBHSTDAT0, data & 0x00ff);
+	host_outb(base, SMBHSTDAT1, (data & 0xff00) >> 8);
+
+	/* Start the command */
+	ret = execute_command(base);
+	if (ret < 0)
+		return ret;
+
+	/* Poll for transaction completion */
+	ret = complete_command(base);
+	if (ret < 0)
+		return ret;
+
+	/* Read results of transaction */
+	*buf = host_inb(base, SMBHSTDAT0);
+	*buf |= (host_inb(base, SMBHSTDAT1) << 8);
+
+	return ret;
+}
+
 int do_smbus_block_write(uintptr_t base, u8 device, u8 cmd, const size_t bytes, const u8 *buf)
 {
 	int ret;