i2c: aspeed: add general call support

This commit adds general call support into Aspeed I2C driver.
This is downstream only customization so it should not go into
upstream.

Signed-off-by: Jae Hyun Yoo <jae.hyun.yoo@intel.com>

4 files changed, 44 insertions, 1 deletions

diff --git a/Documentation/devicetree/bindings/i2c/i2c-aspeed.txt b/Documentation/devicetree/bindings/i2c/i2c-aspeed.txt
index 805edb3d95e7..64358b9c006c 100644
--- a/Documentation/devicetree/bindings/i2c/i2c-aspeed.txt
+++ b/Documentation/devicetree/bindings/i2c/i2c-aspeed.txt
@@ -20,6 +20,7 @@ Optional Properties:
 - bus-frequency	: frequency of the bus clock in Hz defaults to 100 kHz when not
 		  specified
 - multi-master	: states that there is another master active on this bus.
+- general-call	: enables general call receiving.
 - bus-timeout-ms: bus timeout in milliseconds defaults to 1 second when not
 		  specified.
 - #retries	: Number of retries for master transfer.
diff --git a/drivers/i2c/busses/i2c-aspeed.c b/drivers/i2c/busses/i2c-aspeed.c
index 1a6e13c609e4..00cdddebf03c 100644
--- a/drivers/i2c/busses/i2c-aspeed.c
+++ b/drivers/i2c/busses/i2c-aspeed.c
@@ -59,6 +59,7 @@
 #define ASPEED_I2CD_SDA_DRIVE_1T_EN			BIT(8)
 #define ASPEED_I2CD_M_SDA_DRIVE_1T_EN			BIT(7)
 #define ASPEED_I2CD_M_HIGH_SPEED_EN			BIT(6)
+#define ASPEED_I2CD_GCALL_EN				BIT(2)
 #define ASPEED_I2CD_SLAVE_EN				BIT(1)
 #define ASPEED_I2CD_MASTER_EN				BIT(0)
 
@@ -84,6 +85,7 @@
 #define ASPEED_I2CD_INTR_RECV_MASK			0xf000ffff
 #define ASPEED_I2CD_INTR_SDA_DL_TIMEOUT			BIT(14)
 #define ASPEED_I2CD_INTR_BUS_RECOVER_DONE		BIT(13)
+#define ASPEED_I2CD_INTR_GCALL_ADDR			BIT(8)
 #define ASPEED_I2CD_INTR_SLAVE_MATCH			BIT(7)
 #define ASPEED_I2CD_INTR_SCL_TIMEOUT			BIT(6)
 #define ASPEED_I2CD_INTR_ABNORMAL			BIT(5)
@@ -168,6 +170,8 @@ enum aspeed_i2c_slave_state {
 	ASPEED_I2C_SLAVE_READ_PROCESSED,
 	ASPEED_I2C_SLAVE_WRITE_REQUESTED,
 	ASPEED_I2C_SLAVE_WRITE_RECEIVED,
+	ASPEED_I2C_SLAVE_GCALL_START,
+	ASPEED_I2C_SLAVE_GCALL_REQUESTED,
 	ASPEED_I2C_SLAVE_STOP,
 };
 
@@ -209,6 +213,8 @@ struct aspeed_i2c_bus {
 #if IS_ENABLED(CONFIG_I2C_SLAVE)
 	struct i2c_client		*slave;
 	enum aspeed_i2c_slave_state	slave_state;
+	/* General call */
+	bool				general_call;
 #endif /* CONFIG_I2C_SLAVE */
 };
 
@@ -424,6 +430,12 @@ static u32 aspeed_i2c_slave_irq(struct aspeed_i2c_bus *bus, u32 irq_status)
 		bus->slave_state = ASPEED_I2C_SLAVE_START;
 	}
 
+	/* General call was requested, restart state machine. */
+	if (irq_status & ASPEED_I2CD_INTR_GCALL_ADDR) {
+		irq_handled |= ASPEED_I2CD_INTR_GCALL_ADDR;
+		bus->slave_state = ASPEED_I2C_SLAVE_GCALL_START;
+	}
+
 	/* Slave is not currently active, irq was for someone else. */
 	if (bus->slave_state == ASPEED_I2C_SLAVE_INACTIVE)
 		return irq_handled;
@@ -442,6 +454,21 @@ static u32 aspeed_i2c_slave_irq(struct aspeed_i2c_bus *bus, u32 irq_status)
 			else
 				bus->slave_state =
 						ASPEED_I2C_SLAVE_WRITE_REQUESTED;
+		} else if (bus->slave_state == ASPEED_I2C_SLAVE_GCALL_START) {
+			/*
+			 * I2C spec defines the second byte meaning like below.
+			 * 0x06 : Reset and write programmable part of slave
+			 *        address by hardware.
+			 * 0x04 : Write programmable part of slave address by
+			 *        hardware.
+			 * 0x00 : No allowed.
+			 *
+			 * But in OpenBMC, we are going to use this
+			 * 'General call' feature for IPMB message broadcasting
+			 * so it delivers all data as is without any specific
+			 * handling of the second byte.
+			 */
+			bus->slave_state = ASPEED_I2C_SLAVE_GCALL_REQUESTED;
 		}
 		irq_handled |= ASPEED_I2CD_INTR_RX_DONE;
 	}
@@ -488,11 +515,16 @@ static u32 aspeed_i2c_slave_irq(struct aspeed_i2c_bus *bus, u32 irq_status)
 		i2c_slave_event(slave, I2C_SLAVE_WRITE_RECEIVED, &value);
 		aspeed_i2c_slave_handle_write_received(bus, &value);
 		break;
+	case ASPEED_I2C_SLAVE_GCALL_REQUESTED:
+		bus->slave_state = ASPEED_I2C_SLAVE_WRITE_RECEIVED;
+		i2c_slave_event(slave, I2C_SLAVE_GCALL_REQUESTED, &value);
+		break;
 	case ASPEED_I2C_SLAVE_STOP:
 		i2c_slave_event(slave, I2C_SLAVE_STOP, &value);
 		bus->slave_state = ASPEED_I2C_SLAVE_INACTIVE;
 		break;
 	case ASPEED_I2C_SLAVE_START:
+	case ASPEED_I2C_SLAVE_GCALL_START:
 		/* Slave was just started. Waiting for the next event. */;
 		break;
 	default:
@@ -1132,6 +1164,8 @@ static void __aspeed_i2c_reg_slave(struct aspeed_i2c_bus *bus, u16 slave_addr)
 	/* Turn on slave mode. */
 	func_ctrl_reg_val = readl(bus->base + ASPEED_I2C_FUN_CTRL_REG);
 	func_ctrl_reg_val |= ASPEED_I2CD_SLAVE_EN;
+	if (bus->general_call)
+		func_ctrl_reg_val |= ASPEED_I2CD_GCALL_EN;
 	writel(func_ctrl_reg_val, bus->base + ASPEED_I2C_FUN_CTRL_REG);
 }
 
@@ -1170,6 +1204,8 @@ static int aspeed_i2c_unreg_slave(struct i2c_client *client)
 	/* Turn off slave mode. */
 	func_ctrl_reg_val = readl(bus->base + ASPEED_I2C_FUN_CTRL_REG);
 	func_ctrl_reg_val &= ~ASPEED_I2CD_SLAVE_EN;
+	if (bus->general_call)
+		func_ctrl_reg_val &= ~ASPEED_I2CD_GCALL_EN;
 	writel(func_ctrl_reg_val, bus->base + ASPEED_I2C_FUN_CTRL_REG);
 
 	bus->slave = NULL;
@@ -1317,6 +1353,9 @@ static int aspeed_i2c_init(struct aspeed_i2c_bus *bus,
 	       bus->base + ASPEED_I2C_FUN_CTRL_REG);
 
 #if IS_ENABLED(CONFIG_I2C_SLAVE)
+	if (of_property_read_bool(pdev->dev.of_node, "general-call"))
+		bus->general_call = true;
+
 	/* If slave has already been registered, re-enable it. */
 	if (bus->slave)
 		__aspeed_i2c_reg_slave(bus, bus->slave->addr);
diff --git a/drivers/i2c/i2c-slave-mqueue.c b/drivers/i2c/i2c-slave-mqueue.c
index 2c7a6038409c..1d4db584b393 100644
--- a/drivers/i2c/i2c-slave-mqueue.c
+++ b/drivers/i2c/i2c-slave-mqueue.c
@@ -56,10 +56,12 @@ static int i2c_slave_mqueue_callback(struct i2c_client *client,
 
 	switch (event) {
 	case I2C_SLAVE_WRITE_REQUESTED:
+	case I2C_SLAVE_GCALL_REQUESTED:
 		mq->truncated = 0;
 
 		msg->len = 1;
-		msg->buf[0] = client->addr << 1;
+		msg->buf[0] = event == I2C_SLAVE_GCALL_REQUESTED ?
+			      0 : client->addr << 1;
 		break;
 
 	case I2C_SLAVE_WRITE_RECEIVED:
diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index 3493fcde1d03..0d996b722b75 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -367,6 +367,7 @@ enum i2c_slave_event {
 	I2C_SLAVE_WRITE_REQUESTED,
 	I2C_SLAVE_READ_PROCESSED,
 	I2C_SLAVE_WRITE_RECEIVED,
+	I2C_SLAVE_GCALL_REQUESTED,
 	I2C_SLAVE_STOP,
 };