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i2c: aspeed: added slave support for Aspeed I2C driver
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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>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
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Brendan Higgins authored and Wolfram Sang committed Jun 23, 2017
1 parent f327c68 commit f9eb913
Showing 1 changed file with 201 additions and 0 deletions.
201 changes: 201 additions & 0 deletions drivers/i2c/busses/i2c-aspeed.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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 */
Expand All @@ -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)
Expand Down Expand Up @@ -101,6 +103,9 @@
#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,
Expand All @@ -111,6 +116,15 @@ 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;
Expand All @@ -130,6 +144,10 @@ struct aspeed_i2c_bus {
int cmd_err;
/* Protected only by i2c_lock_bus */
int master_xfer_result;
#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);
Expand Down Expand Up @@ -202,6 +220,110 @@ 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)
{
Expand Down Expand Up @@ -427,6 +549,13 @@ 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 */

return aspeed_i2c_master_irq(bus) ? IRQ_HANDLED : IRQ_NONE;
}

Expand Down Expand Up @@ -474,9 +603,75 @@ 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 = i2c_get_adapdata(client->adapter);
unsigned long flags;

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 = i2c_get_adapdata(client->adapter);
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)
Expand Down Expand Up @@ -551,6 +746,12 @@ 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);

Expand Down

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