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Subject[PATCH v9 5/5] i2c: aspeed: added slave support for Aspeed I2C driver
Date
Added slave support for Aspeed I2C controller. Supports fourteen busses
present in AST24XX and AST25XX BMC SoCs by Aspeed.

Signed-off-by: Brendan Higgins <brendanhiggins@google.com>
---
Added in v6:
- Pulled slave support out of initial driver commit into its own commit.
- No longer arbitrarily restrict bus to be slave xor master.
Changes for v7:
- Added hardware reset function
- Marked functions that need to be called with the lock held as "unlocked"
- Did some cleanup
Changes for v8:
- None
Changes for v9:
- None
---
drivers/i2c/busses/i2c-aspeed.c | 202 ++++++++++++++++++++++++++++++++++++++++
1 file changed, 202 insertions(+)

diff --git a/drivers/i2c/busses/i2c-aspeed.c b/drivers/i2c/busses/i2c-aspeed.c
index a80f89fa0ed5..40671a60ddf0 100644
--- a/drivers/i2c/busses/i2c-aspeed.c
+++ b/drivers/i2c/busses/i2c-aspeed.c
@@ -49,6 +49,7 @@
#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_SLAVE_EN BIT(1)
#define ASPEED_I2CD_MASTER_EN BIT(0)

/* 0x04 : I2CD Clock and AC Timing Control Register #1 */
@@ -69,6 +70,7 @@
*/
#define ASPEED_I2CD_INTR_SDA_DL_TIMEOUT BIT(14)
#define ASPEED_I2CD_INTR_BUS_RECOVER_DONE BIT(13)
+#define ASPEED_I2CD_INTR_SLAVE_MATCH BIT(7)
#define ASPEED_I2CD_INTR_SCL_TIMEOUT BIT(6)
#define ASPEED_I2CD_INTR_ABNORMAL BIT(5)
#define ASPEED_I2CD_INTR_NORMAL_STOP BIT(4)
@@ -106,6 +108,9 @@
#define ASPEED_I2CD_M_TX_CMD BIT(1)
#define ASPEED_I2CD_M_START_CMD BIT(0)

+/* 0x18 : I2CD Slave Device Address Register */
+#define ASPEED_I2CD_DEV_ADDR_MASK GENMASK(6, 0)
+
enum aspeed_i2c_master_state {
ASPEED_I2C_MASTER_START,
ASPEED_I2C_MASTER_TX_FIRST,
@@ -116,6 +121,15 @@ enum aspeed_i2c_master_state {
ASPEED_I2C_MASTER_INACTIVE,
};

+enum aspeed_i2c_slave_state {
+ ASPEED_I2C_SLAVE_START,
+ ASPEED_I2C_SLAVE_READ_REQUESTED,
+ ASPEED_I2C_SLAVE_READ_PROCESSED,
+ ASPEED_I2C_SLAVE_WRITE_REQUESTED,
+ ASPEED_I2C_SLAVE_WRITE_RECEIVED,
+ ASPEED_I2C_SLAVE_STOP,
+};
+
struct aspeed_i2c_bus {
struct i2c_adapter adap;
struct device *dev;
@@ -134,6 +148,10 @@ struct aspeed_i2c_bus {
size_t msgs_count;
bool send_stop;
int cmd_err;
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+ struct i2c_client *slave;
+ enum aspeed_i2c_slave_state slave_state;
+#endif /* CONFIG_I2C_SLAVE */
};

static int aspeed_i2c_reset(struct aspeed_i2c_bus *bus);
@@ -205,6 +223,110 @@ static int aspeed_i2c_recover_bus(struct aspeed_i2c_bus *bus)
return aspeed_i2c_reset(bus);
}

+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+static bool aspeed_i2c_slave_irq(struct aspeed_i2c_bus *bus)
+{
+ u32 command, irq_status, status_ack = 0;
+ struct i2c_client *slave = bus->slave;
+ bool irq_handled = true;
+ u8 value;
+
+ spin_lock(&bus->lock);
+ if (!slave) {
+ irq_handled = false;
+ goto out;
+ }
+
+ command = readl(bus->base + ASPEED_I2C_CMD_REG);
+ irq_status = readl(bus->base + ASPEED_I2C_INTR_STS_REG);
+
+ /* Slave was requested, restart state machine. */
+ if (irq_status & ASPEED_I2CD_INTR_SLAVE_MATCH) {
+ status_ack |= ASPEED_I2CD_INTR_SLAVE_MATCH;
+ bus->slave_state = ASPEED_I2C_SLAVE_START;
+ }
+
+ /* Slave is not currently active, irq was for someone else. */
+ if (bus->slave_state == ASPEED_I2C_SLAVE_STOP) {
+ irq_handled = false;
+ goto out;
+ }
+
+ dev_dbg(bus->dev, "slave irq status 0x%08x, cmd 0x%08x\n",
+ irq_status, command);
+
+ /* Slave was sent something. */
+ if (irq_status & ASPEED_I2CD_INTR_RX_DONE) {
+ value = readl(bus->base + ASPEED_I2C_BYTE_BUF_REG) >> 8;
+ /* Handle address frame. */
+ if (bus->slave_state == ASPEED_I2C_SLAVE_START) {
+ if (value & 0x1)
+ bus->slave_state =
+ ASPEED_I2C_SLAVE_READ_REQUESTED;
+ else
+ bus->slave_state =
+ ASPEED_I2C_SLAVE_WRITE_REQUESTED;
+ }
+ status_ack |= ASPEED_I2CD_INTR_RX_DONE;
+ }
+
+ /* Slave was asked to stop. */
+ if (irq_status & ASPEED_I2CD_INTR_NORMAL_STOP) {
+ status_ack |= ASPEED_I2CD_INTR_NORMAL_STOP;
+ bus->slave_state = ASPEED_I2C_SLAVE_STOP;
+ }
+ if (irq_status & ASPEED_I2CD_INTR_TX_NAK) {
+ status_ack |= ASPEED_I2CD_INTR_TX_NAK;
+ bus->slave_state = ASPEED_I2C_SLAVE_STOP;
+ }
+
+ switch (bus->slave_state) {
+ case ASPEED_I2C_SLAVE_READ_REQUESTED:
+ if (irq_status & ASPEED_I2CD_INTR_TX_ACK)
+ dev_err(bus->dev, "Unexpected ACK on read request.\n");
+ bus->slave_state = ASPEED_I2C_SLAVE_READ_PROCESSED;
+
+ i2c_slave_event(slave, I2C_SLAVE_READ_REQUESTED, &value);
+ writel(value, bus->base + ASPEED_I2C_BYTE_BUF_REG);
+ writel(ASPEED_I2CD_S_TX_CMD, bus->base + ASPEED_I2C_CMD_REG);
+ break;
+ case ASPEED_I2C_SLAVE_READ_PROCESSED:
+ status_ack |= ASPEED_I2CD_INTR_TX_ACK;
+ if (!(irq_status & ASPEED_I2CD_INTR_TX_ACK))
+ dev_err(bus->dev,
+ "Expected ACK after processed read.\n");
+ i2c_slave_event(slave, I2C_SLAVE_READ_PROCESSED, &value);
+ writel(value, bus->base + ASPEED_I2C_BYTE_BUF_REG);
+ writel(ASPEED_I2CD_S_TX_CMD, bus->base + ASPEED_I2C_CMD_REG);
+ break;
+ case ASPEED_I2C_SLAVE_WRITE_REQUESTED:
+ bus->slave_state = ASPEED_I2C_SLAVE_WRITE_RECEIVED;
+ i2c_slave_event(slave, I2C_SLAVE_WRITE_REQUESTED, &value);
+ break;
+ case ASPEED_I2C_SLAVE_WRITE_RECEIVED:
+ i2c_slave_event(slave, I2C_SLAVE_WRITE_RECEIVED, &value);
+ break;
+ case ASPEED_I2C_SLAVE_STOP:
+ i2c_slave_event(slave, I2C_SLAVE_STOP, &value);
+ break;
+ default:
+ dev_err(bus->dev, "unhandled slave_state: %d\n",
+ bus->slave_state);
+ break;
+ }
+
+ if (status_ack != irq_status)
+ dev_err(bus->dev,
+ "irq handled != irq. expected %x, but was %x\n",
+ irq_status, status_ack);
+ writel(status_ack, bus->base + ASPEED_I2C_INTR_STS_REG);
+
+out:
+ spin_unlock(&bus->lock);
+ return irq_handled;
+}
+#endif /* CONFIG_I2C_SLAVE */
+
/* precondition: bus.lock has been acquired. */
static void aspeed_i2c_do_start(struct aspeed_i2c_bus *bus)
{
@@ -408,6 +530,13 @@ static irqreturn_t aspeed_i2c_bus_irq(int irq, void *dev_id)
{
struct aspeed_i2c_bus *bus = dev_id;

+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+ if (aspeed_i2c_slave_irq(bus)) {
+ dev_dbg(bus->dev, "irq handled by slave.\n");
+ return IRQ_HANDLED;
+ }
+#endif /* CONFIG_I2C_SLAVE */
+
if (aspeed_i2c_master_irq(bus))
return IRQ_HANDLED;
else
@@ -467,9 +596,76 @@ static u32 aspeed_i2c_functionality(struct i2c_adapter *adap)
return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_SMBUS_BLOCK_DATA;
}

+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+/* precondition: bus.lock has been acquired. */
+static void __aspeed_i2c_reg_slave(struct aspeed_i2c_bus *bus, u16 slave_addr)
+{
+ u32 addr_reg_val, func_ctrl_reg_val;
+
+ /* Set slave addr. */
+ addr_reg_val = readl(bus->base + ASPEED_I2C_DEV_ADDR_REG);
+ addr_reg_val &= ~ASPEED_I2CD_DEV_ADDR_MASK;
+ addr_reg_val |= slave_addr & ASPEED_I2CD_DEV_ADDR_MASK;
+ writel(addr_reg_val, bus->base + ASPEED_I2C_DEV_ADDR_REG);
+
+ /* Turn on slave mode. */
+ func_ctrl_reg_val = readl(bus->base + ASPEED_I2C_FUN_CTRL_REG);
+ func_ctrl_reg_val |= ASPEED_I2CD_SLAVE_EN;
+ writel(func_ctrl_reg_val, bus->base + ASPEED_I2C_FUN_CTRL_REG);
+}
+
+static int aspeed_i2c_reg_slave(struct i2c_client *client)
+{
+ struct aspeed_i2c_bus *bus;
+ unsigned long flags;
+
+ bus = client->adapter->algo_data;
+ spin_lock_irqsave(&bus->lock, flags);
+ if (bus->slave) {
+ spin_unlock_irqrestore(&bus->lock, flags);
+ return -EINVAL;
+ }
+
+ __aspeed_i2c_reg_slave(bus, client->addr);
+
+ bus->slave = client;
+ bus->slave_state = ASPEED_I2C_SLAVE_STOP;
+ spin_unlock_irqrestore(&bus->lock, flags);
+
+ return 0;
+}
+
+static int aspeed_i2c_unreg_slave(struct i2c_client *client)
+{
+ struct aspeed_i2c_bus *bus = client->adapter->algo_data;
+ u32 func_ctrl_reg_val;
+ unsigned long flags;
+
+ spin_lock_irqsave(&bus->lock, flags);
+ if (!bus->slave) {
+ spin_unlock_irqrestore(&bus->lock, flags);
+ return -EINVAL;
+ }
+
+ /* Turn off slave mode. */
+ func_ctrl_reg_val = readl(bus->base + ASPEED_I2C_FUN_CTRL_REG);
+ func_ctrl_reg_val &= ~ASPEED_I2CD_SLAVE_EN;
+ writel(func_ctrl_reg_val, bus->base + ASPEED_I2C_FUN_CTRL_REG);
+
+ bus->slave = NULL;
+ spin_unlock_irqrestore(&bus->lock, flags);
+
+ return 0;
+}
+#endif /* CONFIG_I2C_SLAVE */
+
static const struct i2c_algorithm aspeed_i2c_algo = {
.master_xfer = aspeed_i2c_master_xfer,
.functionality = aspeed_i2c_functionality,
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+ .reg_slave = aspeed_i2c_reg_slave,
+ .unreg_slave = aspeed_i2c_unreg_slave,
+#endif /* CONFIG_I2C_SLAVE */
};

static u32 aspeed_i2c_get_clk_reg_val(u32 divisor)
@@ -544,6 +740,12 @@ static int aspeed_i2c_init(struct aspeed_i2c_bus *bus,
writel(readl(bus->base + ASPEED_I2C_FUN_CTRL_REG) | fun_ctrl_reg,
bus->base + ASPEED_I2C_FUN_CTRL_REG);

+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+ /* If slave has already been registered, re-enable it. */
+ if (bus->slave)
+ __aspeed_i2c_reg_slave(bus, bus->slave->addr);
+#endif /* CONFIG_I2C_SLAVE */
+
/* Set interrupt generation of I2C controller */
writel(ASPEED_I2CD_INTR_ALL, bus->base + ASPEED_I2C_INTR_CTRL_REG);

--
2.13.0.506.g27d5fe0cd-goog
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