[PATCH v4 2/8] i2c: iproc: Add slave mode support

Ray Jui
2019-02-04T23:16:16Z

From: Shreesha Rajashekar <shreesha.rajashekar@broadcom.com>

Add slave mode support to the iProc I2C driver.

Signed-off-by: Rayagonda Kokatanur <rayagonda.kokatanur@broadcom.com>
Signed-off-by: Michael Cheng <ccheng@broadcom.com>
Signed-off-by: Shreesha Rajashekar <shreesha.rajashekar@broadcom.com>
Signed-off-by: Ray Jui <ray.jui@broadcom.com>
---
drivers/i2c/busses/Kconfig | 1 +
drivers/i2c/busses/i2c-bcm-iproc.c | 314 ++++++++++++++++++++++++++++-
2 files changed, 309 insertions(+), 6 deletions(-)

diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index f2c681971201..e0798b82b3bc 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -424,6 +424,7 @@ config I2C_BCM_IPROC
tristate "Broadcom iProc I2C controller"
depends on ARCH_BCM_IPROC || COMPILE_TEST
default ARCH_BCM_IPROC
+ select I2C_SLAVE
help
If you say yes to this option, support will be included for the
Broadcom iProc I2C controller.
diff --git a/drivers/i2c/busses/i2c-bcm-iproc.c b/drivers/i2c/busses/i2c-bcm-iproc.c
index eb7339a0280e..775b3d89a9c4 100644
--- a/drivers/i2c/busses/i2c-bcm-iproc.c
+++ b/drivers/i2c/busses/i2c-bcm-iproc.c
@@ -23,11 +23,30 @@
#define CFG_OFFSET 0x00
#define CFG_RESET_SHIFT 31
#define CFG_EN_SHIFT 30
+#define CFG_SLAVE_ADDR_0_SHIFT 28
#define CFG_M_RETRY_CNT_SHIFT 16
#define CFG_M_RETRY_CNT_MASK 0x0f

#define TIM_CFG_OFFSET 0x04
#define TIM_CFG_MODE_400_SHIFT 31
+#define TIM_RAND_SLAVE_STRETCH_SHIFT 24
+#define TIM_RAND_SLAVE_STRETCH_MASK 0x7f
+#define TIM_PERIODIC_SLAVE_STRETCH_SHIFT 16
+#define TIM_PERIODIC_SLAVE_STRETCH_MASK 0x7f
+
+#define S_CFG_SMBUS_ADDR_OFFSET 0x08
+#define S_CFG_EN_NIC_SMB_ADDR3_SHIFT 31
+#define S_CFG_NIC_SMB_ADDR3_SHIFT 24
+#define S_CFG_NIC_SMB_ADDR3_MASK 0x7f
+#define S_CFG_EN_NIC_SMB_ADDR2_SHIFT 23
+#define S_CFG_NIC_SMB_ADDR2_SHIFT 16
+#define S_CFG_NIC_SMB_ADDR2_MASK 0x7f
+#define S_CFG_EN_NIC_SMB_ADDR1_SHIFT 15
+#define S_CFG_NIC_SMB_ADDR1_SHIFT 8
+#define S_CFG_NIC_SMB_ADDR1_MASK 0x7f
+#define S_CFG_EN_NIC_SMB_ADDR0_SHIFT 7
+#define S_CFG_NIC_SMB_ADDR0_SHIFT 0
+#define S_CFG_NIC_SMB_ADDR0_MASK 0x7f

#define M_FIFO_CTRL_OFFSET 0x0c
#define M_FIFO_RX_FLUSH_SHIFT 31
@@ -37,6 +56,14 @@
#define M_FIFO_RX_THLD_SHIFT 8
#define M_FIFO_RX_THLD_MASK 0x3f

+#define S_FIFO_CTRL_OFFSET 0x10
+#define S_FIFO_RX_FLUSH_SHIFT 31
+#define S_FIFO_TX_FLUSH_SHIFT 30
+#define S_FIFO_RX_CNT_SHIFT 16
+#define S_FIFO_RX_CNT_MASK 0x7f
+#define S_FIFO_RX_THLD_SHIFT 8
+#define S_FIFO_RX_THLD_MASK 0x3f
+
#define M_CMD_OFFSET 0x30
#define M_CMD_START_BUSY_SHIFT 31
#define M_CMD_STATUS_SHIFT 25
@@ -46,6 +73,8 @@
#define M_CMD_STATUS_NACK_ADDR 0x2
#define M_CMD_STATUS_NACK_DATA 0x3
#define M_CMD_STATUS_TIMEOUT 0x4
+#define M_CMD_STATUS_FIFO_UNDERRUN 0x5
+#define M_CMD_STATUS_RX_FIFO_FULL 0x6
#define M_CMD_PROTOCOL_SHIFT 9
#define M_CMD_PROTOCOL_MASK 0xf
#define M_CMD_PROTOCOL_BLK_WR 0x7
@@ -54,17 +83,36 @@
#define M_CMD_RD_CNT_SHIFT 0
#define M_CMD_RD_CNT_MASK 0xff

+#define S_CMD_OFFSET 0x34
+#define S_CMD_START_BUSY_SHIFT 31
+#define S_CMD_STATUS_SHIFT 23
+#define S_CMD_STATUS_MASK 0x07
+#define S_CMD_STATUS_SUCCESS 0x0
+#define S_CMD_STATUS_TIMEOUT 0x5
+
#define IE_OFFSET 0x38
#define IE_M_RX_FIFO_FULL_SHIFT 31
#define IE_M_RX_THLD_SHIFT 30
#define IE_M_START_BUSY_SHIFT 28
#define IE_M_TX_UNDERRUN_SHIFT 27
+#define IE_S_RX_FIFO_FULL_SHIFT 26
+#define IE_S_RX_THLD_SHIFT 25
+#define IE_S_RX_EVENT_SHIFT 24
+#define IE_S_START_BUSY_SHIFT 23
+#define IE_S_TX_UNDERRUN_SHIFT 22
+#define IE_S_RD_EVENT_SHIFT 21

#define IS_OFFSET 0x3c
#define IS_M_RX_FIFO_FULL_SHIFT 31
#define IS_M_RX_THLD_SHIFT 30
#define IS_M_START_BUSY_SHIFT 28
#define IS_M_TX_UNDERRUN_SHIFT 27
+#define IS_S_RX_FIFO_FULL_SHIFT 26
+#define IS_S_RX_THLD_SHIFT 25
+#define IS_S_RX_EVENT_SHIFT 24
+#define IS_S_START_BUSY_SHIFT 23
+#define IS_S_TX_UNDERRUN_SHIFT 22
+#define IS_S_RD_EVENT_SHIFT 21

#define M_TX_OFFSET 0x40
#define M_TX_WR_STATUS_SHIFT 31
@@ -78,6 +126,18 @@
#define M_RX_DATA_SHIFT 0
#define M_RX_DATA_MASK 0xff

+#define S_TX_OFFSET 0x48
+#define S_TX_WR_STATUS_SHIFT 31
+#define S_TX_DATA_SHIFT 0
+#define S_TX_DATA_MASK 0xff
+
+#define S_RX_OFFSET 0x4c
+#define S_RX_STATUS_SHIFT 30
+#define S_RX_STATUS_MASK 0x03
+#define S_RX_PEC_ERR_SHIFT 29
+#define S_RX_DATA_SHIFT 0
+#define S_RX_DATA_MASK 0xff
+
#define I2C_TIMEOUT_MSEC 50000
#define M_TX_RX_FIFO_SIZE 64
#define M_RX_FIFO_MAX_THLD_VALUE (M_TX_RX_FIFO_SIZE - 1)
@@ -85,6 +145,30 @@
#define M_RX_MAX_READ_LEN 255
#define M_RX_FIFO_THLD_VALUE 50

+#define IE_M_ALL_INTERRUPT_SHIFT 27
+#define IE_M_ALL_INTERRUPT_MASK 0x1e
+
+#define SLAVE_READ_WRITE_BIT_MASK 0x1
+#define SLAVE_READ_WRITE_BIT_SHIFT 0x1
+#define SLAVE_MAX_SIZE_TRANSACTION 64
+#define SLAVE_CLOCK_STRETCH_TIME 25
+
+#define IE_S_ALL_INTERRUPT_SHIFT 21
+#define IE_S_ALL_INTERRUPT_MASK 0x3f
+
+enum i2c_slave_read_status {
+ I2C_SLAVE_RX_FIFO_EMPTY = 0,
+ I2C_SLAVE_RX_START,
+ I2C_SLAVE_RX_DATA,
+ I2C_SLAVE_RX_END,
+};
+
+enum i2c_slave_xfer_dir {
+ I2C_SLAVE_DIR_READ = 0,
+ I2C_SLAVE_DIR_WRITE,
+ I2C_SLAVE_DIR_NONE,
+};
+
enum bus_speed_index {
I2C_SPD_100K = 0,
I2C_SPD_400K,
@@ -104,6 +188,9 @@ struct bcm_iproc_i2c_dev {

struct i2c_msg *msg;

+ struct i2c_client *slave;
+ enum i2c_slave_xfer_dir xfer_dir;
+
/* bytes that have been transferred */
unsigned int tx_bytes;
/* bytes that have been read */
@@ -117,6 +204,156 @@ struct bcm_iproc_i2c_dev {
#define ISR_MASK (BIT(IS_M_START_BUSY_SHIFT) | BIT(IS_M_TX_UNDERRUN_SHIFT)\
| BIT(IS_M_RX_THLD_SHIFT))

+#define ISR_MASK_SLAVE (BIT(IS_S_START_BUSY_SHIFT)\
+ | BIT(IS_S_RX_EVENT_SHIFT) | BIT(IS_S_RD_EVENT_SHIFT))
+
+static int bcm_iproc_i2c_reg_slave(struct i2c_client *slave);
+static int bcm_iproc_i2c_unreg_slave(struct i2c_client *slave);
+static void bcm_iproc_i2c_enable_disable(struct bcm_iproc_i2c_dev *iproc_i2c,
+ bool enable);
+
+static void bcm_iproc_i2c_slave_init(
+ struct bcm_iproc_i2c_dev *iproc_i2c, bool need_reset)
+{
+ u32 val;
+
+ if (need_reset) {
+ /* put controller in reset */
+ val = readl(iproc_i2c->base + CFG_OFFSET);
+ val |= BIT(CFG_RESET_SHIFT);
+ writel(val, iproc_i2c->base + CFG_OFFSET);
+
+ /* wait 100 usec per spec */
+ udelay(100);
+
+ /* bring controller out of reset */
+ val &= ~(BIT(CFG_RESET_SHIFT));
+ writel(val, iproc_i2c->base + CFG_OFFSET);
+ }
+
+ /* flush TX/RX FIFOs */
+ val = (BIT(S_FIFO_RX_FLUSH_SHIFT) | BIT(S_FIFO_TX_FLUSH_SHIFT));
+ writel(val, iproc_i2c->base + S_FIFO_CTRL_OFFSET);
+
+ /* RANDOM SLAVE STRETCH time - 20ms*/
+ val = readl(iproc_i2c->base + TIM_CFG_OFFSET);
+ val &= ~(TIM_RAND_SLAVE_STRETCH_MASK << TIM_RAND_SLAVE_STRETCH_SHIFT);
+ val |= (SLAVE_CLOCK_STRETCH_TIME << TIM_RAND_SLAVE_STRETCH_SHIFT);
+ writel(val, iproc_i2c->base + TIM_CFG_OFFSET);
+
+ /* Configure the slave address */
+ val = readl(iproc_i2c->base + S_CFG_SMBUS_ADDR_OFFSET);
+ val |= BIT(S_CFG_EN_NIC_SMB_ADDR3_SHIFT);
+ val &= ~(S_CFG_NIC_SMB_ADDR3_MASK << S_CFG_NIC_SMB_ADDR3_SHIFT);
+ val |= (iproc_i2c->slave->addr << S_CFG_NIC_SMB_ADDR3_SHIFT);
+ writel(val, iproc_i2c->base + S_CFG_SMBUS_ADDR_OFFSET);
+
+ /* clear all pending slave interrupts */
+ writel(ISR_MASK_SLAVE, iproc_i2c->base + IS_OFFSET);
+
+ /* Enable interrupt register for any READ event */
+ val = BIT(IE_S_RD_EVENT_SHIFT);
+ /* Enable interrupt register to indicate a valid byte in receive fifo */
+ val |= BIT(IE_S_RX_EVENT_SHIFT);
+ /* Enable interrupt register for the Slave BUSY command */
+ val |= BIT(IE_S_START_BUSY_SHIFT);
+ writel(val, iproc_i2c->base + IE_OFFSET);
+
+ iproc_i2c->xfer_dir = I2C_SLAVE_DIR_NONE;
+}
+
+static void bcm_iproc_i2c_check_slave_status(
+ struct bcm_iproc_i2c_dev *iproc_i2c)
+{
+ u32 val;
+
+ val = readl(iproc_i2c->base + S_CMD_OFFSET);
+ val = (val >> S_CMD_STATUS_SHIFT) & S_CMD_STATUS_MASK;
+
+ if (val == S_CMD_STATUS_TIMEOUT) {
+ dev_err(iproc_i2c->device, "slave random stretch time timeout\n");
+
+ /* re-initialize i2c for recovery */
+ bcm_iproc_i2c_enable_disable(iproc_i2c, false);
+ bcm_iproc_i2c_slave_init(iproc_i2c, true);
+ bcm_iproc_i2c_enable_disable(iproc_i2c, true);
+ }
+}
+
+static bool bcm_iproc_i2c_slave_isr(struct bcm_iproc_i2c_dev *iproc_i2c,
+ u32 status)
+{
+ u8 value;
+ u32 val;
+ u32 rd_status;
+ u32 tmp;
+
+ /* Start of transaction. check address and populate the direction */
+ if (iproc_i2c->xfer_dir == I2C_SLAVE_DIR_NONE) {
+ tmp = readl(iproc_i2c->base + S_RX_OFFSET);
+ rd_status = (tmp >> S_RX_STATUS_SHIFT) & S_RX_STATUS_MASK;
+ /* This condition checks whether the request is a new request */
+ if (((rd_status == I2C_SLAVE_RX_START) &&
+ (status & BIT(IS_S_RX_EVENT_SHIFT))) ||
+ ((rd_status == I2C_SLAVE_RX_END) &&
+ (status & BIT(IS_S_RD_EVENT_SHIFT)))) {
+
+ /* Last bit is W/R bit.
+ * If 1 then its a read request(by master).
+ */
+ iproc_i2c->xfer_dir = tmp & SLAVE_READ_WRITE_BIT_MASK;
+ if (iproc_i2c->xfer_dir == I2C_SLAVE_DIR_WRITE)
+ i2c_slave_event(iproc_i2c->slave,
+ I2C_SLAVE_READ_REQUESTED, &value);
+ else
+ i2c_slave_event(iproc_i2c->slave,
+ I2C_SLAVE_WRITE_REQUESTED, &value);
+ }
+ }
+
+ /* read request from master */
+ if ((status & BIT(IS_S_RD_EVENT_SHIFT)) &&
+ (iproc_i2c->xfer_dir == I2C_SLAVE_DIR_WRITE)) {
+ i2c_slave_event(iproc_i2c->slave,
+ I2C_SLAVE_READ_PROCESSED, &value);
+ writel(value, iproc_i2c->base + S_TX_OFFSET);
+
+ val = BIT(S_CMD_START_BUSY_SHIFT);
+ writel(val, iproc_i2c->base + S_CMD_OFFSET);
+ }
+
+ /* write request from master */
+ if ((status & BIT(IS_S_RX_EVENT_SHIFT)) &&
+ (iproc_i2c->xfer_dir == I2C_SLAVE_DIR_READ)) {
+ val = readl(iproc_i2c->base + S_RX_OFFSET);
+ /* Its a write request by Master to Slave.
+ * We read data present in receive FIFO
+ */
+ value = (u8)((val >> S_RX_DATA_SHIFT) & S_RX_DATA_MASK);
+ i2c_slave_event(iproc_i2c->slave,
+ I2C_SLAVE_WRITE_RECEIVED, &value);
+
+ /* check the status for the last byte of the transaction */
+ rd_status = (val >> S_RX_STATUS_SHIFT) & S_RX_STATUS_MASK;
+ if (rd_status == I2C_SLAVE_RX_END)
+ iproc_i2c->xfer_dir = I2C_SLAVE_DIR_NONE;
+
+ dev_dbg(iproc_i2c->device, "\nread value = 0x%x\n", value);
+ }
+
+ /* Stop */
+ if (status & BIT(IS_S_START_BUSY_SHIFT)) {
+ i2c_slave_event(iproc_i2c->slave, I2C_SLAVE_STOP, &value);
+ iproc_i2c->xfer_dir = I2C_SLAVE_DIR_NONE;
+ }
+
+ /* clear interrupt status */
+ writel(status, iproc_i2c->base + IS_OFFSET);
+
+ bcm_iproc_i2c_check_slave_status(iproc_i2c);
+ return true;
+}
+
static void bcm_iproc_i2c_read_valid_bytes(struct bcm_iproc_i2c_dev *iproc_i2c)
{
struct i2c_msg *msg = iproc_i2c->msg;
@@ -142,6 +379,18 @@ static irqreturn_t bcm_iproc_i2c_isr(int irq, void *data)
u32 status = readl(iproc_i2c->base + IS_OFFSET);
u32 tmp;

+
+ bool ret;
+ u32 sl_status = status & ISR_MASK_SLAVE;
+
+ if (sl_status) {
+ ret = bcm_iproc_i2c_slave_isr(iproc_i2c, sl_status);
+ if (ret)
+ return IRQ_HANDLED;
+ else
+ return IRQ_NONE;
+ }
+
status &= ISR_MASK;

if (!status)
@@ -224,22 +473,25 @@ static int bcm_iproc_i2c_init(struct bcm_iproc_i2c_dev *iproc_i2c)

/* put controller in reset */
val = readl(iproc_i2c->base + CFG_OFFSET);
- val |= 1 << CFG_RESET_SHIFT;
- val &= ~(1 << CFG_EN_SHIFT);
+ val |= BIT(CFG_RESET_SHIFT);
+ val &= ~(BIT(CFG_EN_SHIFT));
writel(val, iproc_i2c->base + CFG_OFFSET);

/* wait 100 usec per spec */
udelay(100);

/* bring controller out of reset */
- val &= ~(1 << CFG_RESET_SHIFT);
+ val &= ~(BIT(CFG_RESET_SHIFT));
writel(val, iproc_i2c->base + CFG_OFFSET);

/* flush TX/RX FIFOs and set RX FIFO threshold to zero */
- val = (1 << M_FIFO_RX_FLUSH_SHIFT) | (1 << M_FIFO_TX_FLUSH_SHIFT);
+ val = (BIT(M_FIFO_RX_FLUSH_SHIFT) | BIT(M_FIFO_TX_FLUSH_SHIFT));
writel(val, iproc_i2c->base + M_FIFO_CTRL_OFFSET);
/* disable all interrupts */
- writel(0, iproc_i2c->base + IE_OFFSET);
+ val = readl(iproc_i2c->base + IE_OFFSET);
+ val &= ~(IE_M_ALL_INTERRUPT_MASK <<
+ IE_M_ALL_INTERRUPT_SHIFT);
+ writel(val, iproc_i2c->base + IE_OFFSET);

/* clear all pending interrupts */
writel(0xffffffff, iproc_i2c->base + IS_OFFSET);
@@ -288,6 +540,14 @@ static int bcm_iproc_i2c_check_status(struct bcm_iproc_i2c_dev *iproc_i2c,
dev_dbg(iproc_i2c->device, "bus timeout\n");
return -ETIMEDOUT;

+ case M_CMD_STATUS_FIFO_UNDERRUN:
+ dev_dbg(iproc_i2c->device, "FIFO under-run\n");
+ return -ENXIO;
+
+ case M_CMD_STATUS_RX_FIFO_FULL:
+ dev_dbg(iproc_i2c->device, "Master Rx FIFO full > 10ms\n");
+ return -ETIMEDOUT;
+
default:
dev_dbg(iproc_i2c->device, "unknown error code=%d\n", val);

@@ -442,12 +702,14 @@ static int bcm_iproc_i2c_xfer(struct i2c_adapter *adapter,

static uint32_t bcm_iproc_i2c_functionality(struct i2c_adapter *adap)
{
- return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+ return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_SLAVE;
}

static const struct i2c_algorithm bcm_iproc_algo = {
.master_xfer = bcm_iproc_i2c_xfer,
.functionality = bcm_iproc_i2c_functionality,
+ .reg_slave = bcm_iproc_i2c_reg_slave,
+ .unreg_slave = bcm_iproc_i2c_unreg_slave,
};

static struct i2c_adapter_quirks bcm_iproc_i2c_quirks = {
@@ -612,6 +874,46 @@ static const struct dev_pm_ops bcm_iproc_i2c_pm_ops = {
#define BCM_IPROC_I2C_PM_OPS NULL
#endif /* CONFIG_PM_SLEEP */

+
+static int bcm_iproc_i2c_reg_slave(struct i2c_client *slave)
+{
+ struct bcm_iproc_i2c_dev *iproc_i2c = i2c_get_adapdata(slave->adapter);
+
+ if (iproc_i2c->slave)
+ return -EBUSY;
+
+ if (slave->flags & I2C_CLIENT_TEN)
+ return -EAFNOSUPPORT;
+
+ iproc_i2c->slave = slave;
+ bcm_iproc_i2c_slave_init(iproc_i2c, false);
+ return 0;
+}
+
+static int bcm_iproc_i2c_unreg_slave(struct i2c_client *slave)
+{
+ u32 tmp;
+ struct bcm_iproc_i2c_dev *iproc_i2c = i2c_get_adapdata(slave->adapter);
+
+ if (!iproc_i2c->slave)
+ return -EINVAL;
+
+ iproc_i2c->slave = NULL;
+
+ /* disable all slave interrupts */
+ tmp = readl(iproc_i2c->base + IE_OFFSET);
+ tmp &= ~(IE_S_ALL_INTERRUPT_MASK <<
+ IE_S_ALL_INTERRUPT_SHIFT);
+ writel(tmp, iproc_i2c->base + IE_OFFSET);
+
+ /* Erase the slave address programmed */
+ tmp = readl(iproc_i2c->base + S_CFG_SMBUS_ADDR_OFFSET);
+ tmp &= ~BIT(S_CFG_EN_NIC_SMB_ADDR3_SHIFT);
+ writel(tmp, iproc_i2c->base + S_CFG_SMBUS_ADDR_OFFSET);
+
+ return 0;
+}
+
static const struct of_device_id bcm_iproc_i2c_of_match[] = {
{ .compatible = "brcm,iproc-i2c" },
{ /* sentinel */ }
--
2.17.1