[PATCH v28 4/4] i2c: ast2600: Add target mode support

Ryan Chen
2026-03-30T08:23:10Z

Add target mode support to the AST2600 I2C driver.

Target mode features implemented include:
- Add target interrupt handling
- Address match and response logic
- Separate Tx/Rx DMA address and length configuration

This complements the existing controller-mode support, enabling
dual-role capability.

Signed-off-by: Ryan Chen <ryan_chen@aspeedtech.com>
---
Changes in v28:
- fix typo condication -> condition
- fix compile error, when disable CONFIG_I2C_SLAVE
Changes in v26:
- change int to bool target_operate
- rename target_operate to target_active
- use i2c_bus->target replace require IO
- use WRITE_ONCE replace target_operate write.
---
drivers/i2c/busses/i2c-ast2600.c | 566 +++++++++++++++++++++++++++++++++++++++
1 file changed, 566 insertions(+)

diff --git a/drivers/i2c/busses/i2c-ast2600.c b/drivers/i2c/busses/i2c-ast2600.c
index c2368ba309a7..a9b77917a1fe 100644
--- a/drivers/i2c/busses/i2c-ast2600.c
+++ b/drivers/i2c/busses/i2c-ast2600.c
@@ -274,6 +274,13 @@ struct ast2600_i2c_bus {
void __iomem *buf_base;
int (*setup_tx)(u32 cmd, struct ast2600_i2c_bus *i2c_bus);
int (*setup_rx)(u32 cmd, struct ast2600_i2c_bus *i2c_bus);
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+ /* target structure */
+ bool target_active;
+ unsigned char *target_dma_buf;
+ dma_addr_t target_dma_addr;
+ struct i2c_client *target;
+#endif
};

static void ast2600_i2c_ac_timing_config(struct ast2600_i2c_bus *i2c_bus)
@@ -357,6 +364,440 @@ static int ast2600_i2c_recover_bus(struct ast2600_i2c_bus *i2c_bus)
return ret;
}

+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+static void ast2600_i2c_target_packet_dma_irq(struct ast2600_i2c_bus *i2c_bus, u32 sts)
+{
+ int target_rx_len = 0;
+ u32 cmd = 0;
+ u8 value;
+ int i;
+
+ sts &= ~(AST2600_I2CS_SLAVE_PENDING);
+ /* Handle i2c target timeout condition */
+ if (sts & AST2600_I2CS_INACTIVE_TO) {
+ /* Reset timeout counter */
+ u32 ac_timing = readl(i2c_bus->reg_base + AST2600_I2CC_AC_TIMING) &
+ AST2600_I2CC_AC_TIMING_MASK;
+
+ writel(ac_timing, i2c_bus->reg_base + AST2600_I2CC_AC_TIMING);
+ ac_timing |= AST2600_I2CC_TTIMEOUT(i2c_bus->timeout);
+ writel(ac_timing, i2c_bus->reg_base + AST2600_I2CC_AC_TIMING);
+ cmd = TARGET_TRIGGER_CMD | AST2600_I2CS_RX_DMA_EN;
+ writel(AST2600_I2CS_SET_RX_DMA_LEN(I2C_TARGET_MSG_BUF_SIZE),
+ i2c_bus->reg_base + AST2600_I2CS_DMA_LEN);
+ writel(cmd, i2c_bus->reg_base + AST2600_I2CS_CMD_STS);
+ writel(AST2600_I2CS_PKT_DONE, i2c_bus->reg_base + AST2600_I2CS_ISR);
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_STOP, &value);
+ return;
+ }
+
+ sts &= ~(AST2600_I2CS_PKT_DONE | AST2600_I2CS_PKT_ERROR);
+
+ switch (sts) {
+ case AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_RX_DONE | AST2600_I2CS_WAIT_RX_DMA:
+ case AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_WAIT_RX_DMA:
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_WRITE_REQUESTED, &value);
+ target_rx_len = AST2600_I2C_GET_RX_DMA_LEN(readl(i2c_bus->reg_base +
+ AST2600_I2CS_DMA_LEN_STS));
+ for (i = 0; i < target_rx_len; i++) {
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_WRITE_RECEIVED,
+ &i2c_bus->target_dma_buf[i]);
+ }
+ writel(AST2600_I2CS_SET_RX_DMA_LEN(I2C_TARGET_MSG_BUF_SIZE),
+ i2c_bus->reg_base + AST2600_I2CS_DMA_LEN);
+ cmd = TARGET_TRIGGER_CMD | AST2600_I2CS_RX_DMA_EN;
+ break;
+ case AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_STOP:
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_STOP, &value);
+ writel(AST2600_I2CS_SET_RX_DMA_LEN(I2C_TARGET_MSG_BUF_SIZE),
+ i2c_bus->reg_base + AST2600_I2CS_DMA_LEN);
+ cmd = TARGET_TRIGGER_CMD | AST2600_I2CS_RX_DMA_EN;
+ break;
+ case AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_RX_DONE_NAK |
+ AST2600_I2CS_RX_DONE | AST2600_I2CS_STOP:
+ case AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_WAIT_RX_DMA |
+ AST2600_I2CS_RX_DONE | AST2600_I2CS_STOP:
+ case AST2600_I2CS_RX_DONE_NAK | AST2600_I2CS_RX_DONE | AST2600_I2CS_STOP:
+ case AST2600_I2CS_RX_DONE | AST2600_I2CS_WAIT_RX_DMA | AST2600_I2CS_STOP:
+ case AST2600_I2CS_RX_DONE | AST2600_I2CS_STOP:
+ case AST2600_I2CS_RX_DONE | AST2600_I2CS_WAIT_RX_DMA:
+ case AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_RX_DONE | AST2600_I2CS_STOP:
+ if (sts & AST2600_I2CS_SLAVE_MATCH)
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_WRITE_REQUESTED, &value);
+
+ target_rx_len = AST2600_I2C_GET_RX_DMA_LEN(readl(i2c_bus->reg_base +
+ AST2600_I2CS_DMA_LEN_STS));
+ for (i = 0; i < target_rx_len; i++) {
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_WRITE_RECEIVED,
+ &i2c_bus->target_dma_buf[i]);
+ }
+ writel(AST2600_I2CS_SET_RX_DMA_LEN(I2C_TARGET_MSG_BUF_SIZE),
+ i2c_bus->reg_base + AST2600_I2CS_DMA_LEN);
+ if (sts & AST2600_I2CS_STOP)
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_STOP, &value);
+ cmd = TARGET_TRIGGER_CMD | AST2600_I2CS_RX_DMA_EN;
+ break;
+
+ /* it is Mw data Mr coming -> it need send tx */
+ case AST2600_I2CS_RX_DONE | AST2600_I2CS_WAIT_TX_DMA:
+ case AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_RX_DONE | AST2600_I2CS_WAIT_TX_DMA:
+ /* it should be repeat start read */
+ if (sts & AST2600_I2CS_SLAVE_MATCH)
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_WRITE_REQUESTED, &value);
+
+ target_rx_len = AST2600_I2C_GET_RX_DMA_LEN(readl(i2c_bus->reg_base +
+ AST2600_I2CS_DMA_LEN_STS));
+ for (i = 0; i < target_rx_len; i++) {
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_WRITE_RECEIVED,
+ &i2c_bus->target_dma_buf[i]);
+ }
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_READ_REQUESTED,
+ &i2c_bus->target_dma_buf[0]);
+ writel(AST2600_I2CS_SET_TX_DMA_LEN(1),
+ i2c_bus->reg_base + AST2600_I2CS_DMA_LEN);
+ cmd = TARGET_TRIGGER_CMD | AST2600_I2CS_TX_DMA_EN;
+ break;
+ case AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_WAIT_TX_DMA:
+ /* First Start read */
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_READ_REQUESTED,
+ &i2c_bus->target_dma_buf[0]);
+ writel(AST2600_I2CS_SET_TX_DMA_LEN(1),
+ i2c_bus->reg_base + AST2600_I2CS_DMA_LEN);
+ cmd = TARGET_TRIGGER_CMD | AST2600_I2CS_TX_DMA_EN;
+ break;
+ case AST2600_I2CS_WAIT_TX_DMA:
+ /* it should be next start read */
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_READ_PROCESSED,
+ &i2c_bus->target_dma_buf[0]);
+ writel(AST2600_I2CS_SET_TX_DMA_LEN(1),
+ i2c_bus->reg_base + AST2600_I2CS_DMA_LEN);
+ cmd = TARGET_TRIGGER_CMD | AST2600_I2CS_TX_DMA_EN;
+ break;
+ case AST2600_I2CS_TX_NAK | AST2600_I2CS_STOP:
+ /* it just tx complete */
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_STOP, &value);
+ writel(AST2600_I2CS_SET_RX_DMA_LEN(I2C_TARGET_MSG_BUF_SIZE),
+ i2c_bus->reg_base + AST2600_I2CS_DMA_LEN);
+ cmd = TARGET_TRIGGER_CMD | AST2600_I2CS_RX_DMA_EN;
+ break;
+ case AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_RX_DONE:
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_WRITE_REQUESTED, &value);
+ break;
+ case AST2600_I2CS_STOP:
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_STOP, &value);
+ break;
+ default:
+ dev_dbg(i2c_bus->dev, "unhandled target isr case %x, sts %x\n", sts,
+ readl(i2c_bus->reg_base + AST2600_I2CC_STS_AND_BUFF));
+ break;
+ }
+
+ if (cmd)
+ writel(cmd, i2c_bus->reg_base + AST2600_I2CS_CMD_STS);
+ writel(AST2600_I2CS_PKT_DONE, i2c_bus->reg_base + AST2600_I2CS_ISR);
+ readl(i2c_bus->reg_base + AST2600_I2CS_ISR);
+}
+
+static void ast2600_i2c_target_packet_buff_irq(struct ast2600_i2c_bus *i2c_bus, u32 sts)
+{
+ int target_rx_len = 0;
+ u32 cmd = 0;
+ u8 value;
+ int i;
+
+ /* due to controller target is common buffer, need force the master stop not issue */
+ if (readl(i2c_bus->reg_base + AST2600_I2CM_CMD_STS) & GENMASK(15, 0)) {
+ writel(0, i2c_bus->reg_base + AST2600_I2CM_CMD_STS);
+ i2c_bus->cmd_err = -EBUSY;
+ writel(0, i2c_bus->reg_base + AST2600_I2CC_BUFF_CTRL);
+ complete(&i2c_bus->cmd_complete);
+ }
+
+ /* Handle i2c target timeout condition */
+ if (AST2600_I2CS_INACTIVE_TO & sts) {
+ /* Reset timeout counter */
+ u32 ac_timing = readl(i2c_bus->reg_base + AST2600_I2CC_AC_TIMING) &
+ AST2600_I2CC_AC_TIMING_MASK;
+
+ writel(ac_timing, i2c_bus->reg_base + AST2600_I2CC_AC_TIMING);
+ ac_timing |= AST2600_I2CC_TTIMEOUT(i2c_bus->timeout);
+ writel(ac_timing, i2c_bus->reg_base + AST2600_I2CC_AC_TIMING);
+ writel(TARGET_TRIGGER_CMD, i2c_bus->reg_base + AST2600_I2CS_CMD_STS);
+ writel(AST2600_I2CS_PKT_DONE, i2c_bus->reg_base + AST2600_I2CS_ISR);
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_STOP, &value);
+ WRITE_ONCE(i2c_bus->target_active, false);
+ return;
+ }
+
+ sts &= ~(AST2600_I2CS_PKT_DONE | AST2600_I2CS_PKT_ERROR);
+
+ if (sts & AST2600_I2CS_SLAVE_MATCH)
+ WRITE_ONCE(i2c_bus->target_active, true);
+
+ switch (sts) {
+ case AST2600_I2CS_SLAVE_PENDING | AST2600_I2CS_WAIT_RX_DMA |
+ AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_RX_DONE | AST2600_I2CS_STOP:
+ case AST2600_I2CS_SLAVE_PENDING |
+ AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_RX_DONE | AST2600_I2CS_STOP:
+ case AST2600_I2CS_SLAVE_PENDING |
+ AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_STOP:
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_STOP, &value);
+ fallthrough;
+ case AST2600_I2CS_SLAVE_PENDING |
+ AST2600_I2CS_WAIT_RX_DMA | AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_RX_DONE:
+ case AST2600_I2CS_WAIT_RX_DMA | AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_RX_DONE:
+ case AST2600_I2CS_WAIT_RX_DMA | AST2600_I2CS_SLAVE_MATCH:
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_WRITE_REQUESTED, &value);
+ cmd = TARGET_TRIGGER_CMD;
+ if (sts & AST2600_I2CS_RX_DONE) {
+ target_rx_len = AST2600_I2CC_GET_RX_BUF_LEN(readl(i2c_bus->reg_base +
+ AST2600_I2CC_BUFF_CTRL));
+ for (i = 0; i < target_rx_len; i++) {
+ value = readb(i2c_bus->buf_base + 0x10 + i);
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_WRITE_RECEIVED, &value);
+ }
+ }
+ if (readl(i2c_bus->reg_base + AST2600_I2CS_CMD_STS) & AST2600_I2CS_RX_BUFF_EN)
+ cmd = 0;
+ else
+ cmd = TARGET_TRIGGER_CMD | AST2600_I2CS_RX_BUFF_EN;
+
+ writel(AST2600_I2CC_SET_RX_BUF_LEN(i2c_bus->buf_size),
+ i2c_bus->reg_base + AST2600_I2CC_BUFF_CTRL);
+ break;
+ case AST2600_I2CS_WAIT_RX_DMA | AST2600_I2CS_RX_DONE:
+ cmd = TARGET_TRIGGER_CMD;
+ target_rx_len = AST2600_I2CC_GET_RX_BUF_LEN(readl(i2c_bus->reg_base +
+ AST2600_I2CC_BUFF_CTRL));
+ for (i = 0; i < target_rx_len; i++) {
+ value = readb(i2c_bus->buf_base + 0x10 + i);
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_WRITE_RECEIVED, &value);
+ }
+ cmd |= AST2600_I2CS_RX_BUFF_EN;
+ writel(AST2600_I2CC_SET_RX_BUF_LEN(i2c_bus->buf_size),
+ i2c_bus->reg_base + AST2600_I2CC_BUFF_CTRL);
+ break;
+ case AST2600_I2CS_SLAVE_PENDING | AST2600_I2CS_WAIT_RX_DMA |
+ AST2600_I2CS_RX_DONE | AST2600_I2CS_STOP:
+ cmd = TARGET_TRIGGER_CMD;
+ target_rx_len = AST2600_I2CC_GET_RX_BUF_LEN(readl(i2c_bus->reg_base +
+ AST2600_I2CC_BUFF_CTRL));
+ for (i = 0; i < target_rx_len; i++) {
+ value = readb(i2c_bus->buf_base + 0x10 + i);
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_WRITE_RECEIVED, &value);
+ }
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_STOP, &value);
+ cmd |= AST2600_I2CS_RX_BUFF_EN;
+ writel(AST2600_I2CC_SET_RX_BUF_LEN(i2c_bus->buf_size),
+ i2c_bus->reg_base + AST2600_I2CC_BUFF_CTRL);
+ break;
+ case AST2600_I2CS_SLAVE_PENDING | AST2600_I2CS_RX_DONE | AST2600_I2CS_STOP:
+ cmd = TARGET_TRIGGER_CMD;
+ target_rx_len = AST2600_I2CC_GET_RX_BUF_LEN(readl(i2c_bus->reg_base +
+ AST2600_I2CC_BUFF_CTRL));
+ for (i = 0; i < target_rx_len; i++) {
+ value = readb(i2c_bus->buf_base + 0x10 + i);
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_WRITE_RECEIVED, &value);
+ }
+ /* workaround for avoid next start with len != 0 */
+ writel(BIT(0), i2c_bus->reg_base + AST2600_I2CC_BUFF_CTRL);
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_STOP, &value);
+ break;
+ case AST2600_I2CS_RX_DONE | AST2600_I2CS_STOP:
+ cmd = TARGET_TRIGGER_CMD;
+ target_rx_len = AST2600_I2CC_GET_RX_BUF_LEN(readl(i2c_bus->reg_base +
+ AST2600_I2CC_BUFF_CTRL));
+ for (i = 0; i < target_rx_len; i++) {
+ value = readb(i2c_bus->buf_base + 0x10 + i);
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_WRITE_RECEIVED, &value);
+ }
+ /* workaround for avoid next start with len != 0 */
+ writel(BIT(0), i2c_bus->reg_base + AST2600_I2CC_BUFF_CTRL);
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_STOP, &value);
+ break;
+ case AST2600_I2CS_SLAVE_PENDING | AST2600_I2CS_RX_DONE |
+ AST2600_I2CS_WAIT_TX_DMA | AST2600_I2CS_STOP:
+ target_rx_len = AST2600_I2CC_GET_RX_BUF_LEN(readl(i2c_bus->reg_base +
+ AST2600_I2CC_BUFF_CTRL));
+ for (i = 0; i < target_rx_len; i++) {
+ value = readb(i2c_bus->buf_base + 0x10 + i);
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_WRITE_RECEIVED, &value);
+ }
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_STOP, &value);
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_READ_REQUESTED, &value);
+ writeb(value, i2c_bus->buf_base);
+ break;
+ case AST2600_I2CS_WAIT_TX_DMA | AST2600_I2CS_SLAVE_MATCH:
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_READ_REQUESTED, &value);
+ writeb(value, i2c_bus->buf_base);
+ writel(AST2600_I2CC_SET_TX_BUF_LEN(1),
+ i2c_bus->reg_base + AST2600_I2CC_BUFF_CTRL);
+ cmd = TARGET_TRIGGER_CMD | AST2600_I2CS_TX_BUFF_EN;
+ break;
+ case AST2600_I2CS_SLAVE_PENDING | AST2600_I2CS_STOP |
+ AST2600_I2CS_TX_NAK | AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_RX_DONE:
+ case AST2600_I2CS_SLAVE_PENDING | AST2600_I2CS_WAIT_RX_DMA | AST2600_I2CS_STOP |
+ AST2600_I2CS_TX_NAK | AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_RX_DONE:
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_STOP, &value);
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_WRITE_REQUESTED, &value);
+ target_rx_len = AST2600_I2CC_GET_RX_BUF_LEN(readl(i2c_bus->reg_base +
+ AST2600_I2CC_BUFF_CTRL));
+ for (i = 0; i < target_rx_len; i++) {
+ value = readb(i2c_bus->buf_base + 0x10 + i);
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_WRITE_RECEIVED, &value);
+ }
+ writel(AST2600_I2CC_SET_RX_BUF_LEN(i2c_bus->buf_size),
+ i2c_bus->reg_base + AST2600_I2CC_BUFF_CTRL);
+ cmd = TARGET_TRIGGER_CMD | AST2600_I2CS_RX_BUFF_EN;
+ break;
+ case AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_WAIT_TX_DMA | AST2600_I2CS_RX_DONE:
+ case AST2600_I2CS_WAIT_TX_DMA | AST2600_I2CS_RX_DONE:
+ case AST2600_I2CS_WAIT_TX_DMA:
+ if (sts & AST2600_I2CS_SLAVE_MATCH)
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_WRITE_REQUESTED, &value);
+
+ if (sts & AST2600_I2CS_RX_DONE) {
+ target_rx_len = AST2600_I2CC_GET_RX_BUF_LEN(readl(i2c_bus->reg_base +
+ AST2600_I2CC_BUFF_CTRL));
+ for (i = 0; i < target_rx_len; i++) {
+ value = readb(i2c_bus->buf_base + 0x10 + i);
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_WRITE_RECEIVED, &value);
+ }
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_READ_REQUESTED, &value);
+ } else {
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_READ_PROCESSED, &value);
+ }
+ writeb(value, i2c_bus->buf_base);
+ writel(AST2600_I2CC_SET_TX_BUF_LEN(1),
+ i2c_bus->reg_base + AST2600_I2CC_BUFF_CTRL);
+ cmd = TARGET_TRIGGER_CMD | AST2600_I2CS_TX_BUFF_EN;
+ break;
+ /* workaround : trigger the cmd twice to fix next state keep 1000000 */
+ case AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_RX_DONE:
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_WRITE_REQUESTED, &value);
+ cmd = TARGET_TRIGGER_CMD | AST2600_I2CS_RX_BUFF_EN;
+ writel(cmd, i2c_bus->reg_base + AST2600_I2CS_CMD_STS);
+ break;
+ case AST2600_I2CS_TX_NAK | AST2600_I2CS_STOP:
+ case AST2600_I2CS_STOP:
+ cmd = TARGET_TRIGGER_CMD;
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_STOP, &value);
+ break;
+ default:
+ dev_dbg(i2c_bus->dev, "unhandled target isr case %x, sts %x\n", sts,
+ readl(i2c_bus->reg_base + AST2600_I2CC_STS_AND_BUFF));
+ break;
+ }
+
+ if (cmd)
+ writel(cmd, i2c_bus->reg_base + AST2600_I2CS_CMD_STS);
+ writel(AST2600_I2CS_PKT_DONE, i2c_bus->reg_base + AST2600_I2CS_ISR);
+ readl(i2c_bus->reg_base + AST2600_I2CS_ISR);
+
+ if ((sts & AST2600_I2CS_STOP) && !(sts & AST2600_I2CS_SLAVE_PENDING))
+ WRITE_ONCE(i2c_bus->target_active, false);
+}
+
+static void ast2600_i2c_target_byte_irq(struct ast2600_i2c_bus *i2c_bus, u32 sts)
+{
+ u32 i2c_buff = readl(i2c_bus->reg_base + AST2600_I2CC_STS_AND_BUFF);
+ u32 cmd = AST2600_I2CS_ACTIVE_ALL;
+ u8 byte_data;
+ u8 value;
+
+ /* Handle i2c target timeout condition */
+ if (sts & AST2600_I2CS_INACTIVE_TO) {
+ /* Reset timeout counter */
+ u32 ac_timing = readl(i2c_bus->reg_base + AST2600_I2CC_AC_TIMING) &
+ AST2600_I2CC_AC_TIMING_MASK;
+
+ writel(ac_timing, i2c_bus->reg_base + AST2600_I2CC_AC_TIMING);
+ ac_timing |= AST2600_I2CC_TTIMEOUT(i2c_bus->timeout);
+ writel(ac_timing, i2c_bus->reg_base + AST2600_I2CC_AC_TIMING);
+ writel(AST2600_I2CS_ACTIVE_ALL, i2c_bus->reg_base + AST2600_I2CS_CMD_STS);
+ writel(sts, i2c_bus->reg_base + AST2600_I2CS_ISR);
+ readl(i2c_bus->reg_base + AST2600_I2CS_ISR);
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_STOP, &value);
+ WRITE_ONCE(i2c_bus->target_active, false);
+ return;
+ }
+
+ switch (sts) {
+ case AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_RX_DONE | AST2600_I2CS_WAIT_RX_DMA:
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_WRITE_REQUESTED, &value);
+ /* first address match is address */
+ byte_data = AST2600_I2CC_GET_RX_BUFF(i2c_buff);
+ break;
+ case AST2600_I2CS_RX_DONE | AST2600_I2CS_WAIT_RX_DMA:
+ byte_data = AST2600_I2CC_GET_RX_BUFF(i2c_buff);
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_WRITE_RECEIVED, &byte_data);
+ break;
+ case AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_RX_DONE | AST2600_I2CS_WAIT_TX_DMA:
+ cmd |= AST2600_I2CS_TX_CMD;
+ byte_data = AST2600_I2CC_GET_RX_BUFF(i2c_buff);
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_READ_REQUESTED, &byte_data);
+ writel(byte_data, i2c_bus->reg_base + AST2600_I2CC_STS_AND_BUFF);
+ break;
+ case AST2600_I2CS_TX_ACK | AST2600_I2CS_WAIT_TX_DMA:
+ cmd |= AST2600_I2CS_TX_CMD;
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_READ_PROCESSED, &byte_data);
+ writel(byte_data, i2c_bus->reg_base + AST2600_I2CC_STS_AND_BUFF);
+ break;
+ case AST2600_I2CS_STOP:
+ case AST2600_I2CS_STOP | AST2600_I2CS_TX_NAK:
+ i2c_slave_event(i2c_bus->target, I2C_SLAVE_STOP, &value);
+ break;
+ default:
+ dev_dbg(i2c_bus->dev, "unhandled pkt isr %x\n", sts);
+ break;
+ }
+ writel(cmd, i2c_bus->reg_base + AST2600_I2CS_CMD_STS);
+ writel(sts, i2c_bus->reg_base + AST2600_I2CS_ISR);
+ readl(i2c_bus->reg_base + AST2600_I2CS_ISR);
+}
+
+static int ast2600_i2c_target_irq(struct ast2600_i2c_bus *i2c_bus)
+{
+ u32 ier = readl(i2c_bus->reg_base + AST2600_I2CS_IER);
+ u32 isr = readl(i2c_bus->reg_base + AST2600_I2CS_ISR);
+
+ if (!(isr & ier))
+ return 0;
+
+ /*
+ * Target interrupt coming after controller packet done
+ * So need handle controller first.
+ */
+ if (readl(i2c_bus->reg_base + AST2600_I2CM_ISR) & AST2600_I2CM_PKT_DONE)
+ return 0;
+
+ isr &= ~(AST2600_I2CS_ADDR_INDICATE_MASK);
+
+ if (AST2600_I2CS_ADDR1_NAK & isr)
+ isr &= ~AST2600_I2CS_ADDR1_NAK;
+
+ if (AST2600_I2CS_ADDR2_NAK & isr)
+ isr &= ~AST2600_I2CS_ADDR2_NAK;
+
+ if (AST2600_I2CS_ADDR3_NAK & isr)
+ isr &= ~AST2600_I2CS_ADDR3_NAK;
+
+ if (AST2600_I2CS_ADDR_MASK & isr)
+ isr &= ~AST2600_I2CS_ADDR_MASK;
+
+ if (AST2600_I2CS_PKT_DONE & isr) {
+ if (i2c_bus->mode == DMA_MODE)
+ ast2600_i2c_target_packet_dma_irq(i2c_bus, isr);
+ else
+ ast2600_i2c_target_packet_buff_irq(i2c_bus, isr);
+ } else {
+ ast2600_i2c_target_byte_irq(i2c_bus, isr);
+ }
+
+ return 1;
+}
+#endif
+
static int ast2600_i2c_setup_dma_tx(u32 cmd, struct ast2600_i2c_bus *i2c_bus)
{
struct i2c_msg *msg = &i2c_bus->msgs[i2c_bus->msgs_index];
@@ -629,6 +1070,20 @@ static void ast2600_i2c_controller_packet_irq(struct ast2600_i2c_bus *i2c_bus, u
}
break;
case AST2600_I2CM_RX_DONE:
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+ /*
+ * Workaround for controller/target packet mode enable rx done stuck issue
+ * When controller go for first read (RX_DONE), target mode will also effect
+ * Then controller will send nack, not operate anymore.
+ */
+ if (readl(i2c_bus->reg_base + AST2600_I2CS_CMD_STS) & AST2600_I2CS_PKT_MODE_EN) {
+ u32 target_cmd = readl(i2c_bus->reg_base + AST2600_I2CS_CMD_STS);
+
+ writel(0, i2c_bus->reg_base + AST2600_I2CS_CMD_STS);
+ writel(target_cmd, i2c_bus->reg_base + AST2600_I2CS_CMD_STS);
+ }
+ fallthrough;
+#endif
case AST2600_I2CM_RX_DONE | AST2600_I2CM_NORMAL_STOP:
/* do next rx */
if (i2c_bus->mode == DMA_MODE) {
@@ -727,6 +1182,12 @@ static irqreturn_t ast2600_i2c_bus_irq(int irq, void *dev_id)
{
struct ast2600_i2c_bus *i2c_bus = dev_id;

+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+ if (i2c_bus->target) {
+ if (ast2600_i2c_target_irq(i2c_bus))
+ return IRQ_HANDLED;
+ }
+#endif
return IRQ_RETVAL(ast2600_i2c_controller_irq(i2c_bus));
}

@@ -743,12 +1204,35 @@ static int ast2600_i2c_controller_xfer(struct i2c_adapter *adap, struct i2c_msg
return ret;
}

+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+ if (i2c_bus->mode == BUFF_MODE) {
+ if (i2c_bus->target_active)
+ return -EBUSY;
+ /**
+ * In BUFF_MODE, controller and target share the same buffer register,
+ * A target transaction can update buffer state asynchronously via IRQ,
+ * so block controller transfers while target is active, otherwise we can
+ * corrupt buffer.
+ */
+ writel(0, i2c_bus->reg_base + AST2600_I2CS_IER);
+ if (readl(i2c_bus->reg_base + AST2600_I2CS_ISR) || i2c_bus->target_active) {
+ writel(AST2600_I2CS_PKT_DONE, i2c_bus->reg_base + AST2600_I2CS_IER);
+ return -EBUSY;
+ }
+ }
+#endif
+
i2c_bus->cmd_err = 0;
i2c_bus->msgs = msgs;
i2c_bus->msgs_index = 0;
i2c_bus->msgs_count = num;
reinit_completion(&i2c_bus->cmd_complete);
ret = ast2600_i2c_do_start(i2c_bus);
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+ /* avoid race condition target is wait and controller wait 1st target operate */
+ if (i2c_bus->mode == BUFF_MODE)
+ writel(AST2600_I2CS_PKT_DONE, i2c_bus->reg_base + AST2600_I2CS_IER);
+#endif
if (ret)
goto controller_out;
timeout = wait_for_completion_timeout(&i2c_bus->cmd_complete, i2c_bus->adap.timeout);
@@ -767,6 +1251,9 @@ static int ast2600_i2c_controller_xfer(struct i2c_adapter *adap, struct i2c_msg
* if the bus is still busy.
*/
if (i2c_bus->multi_master &&
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+ !i2c_bus->target_active &&
+#endif
(readl(i2c_bus->reg_base + AST2600_I2CC_STS_AND_BUFF) &
AST2600_I2CC_BUS_BUSY_STS))
ast2600_i2c_recover_bus(i2c_bus);
@@ -814,8 +1301,80 @@ static int ast2600_i2c_init(struct ast2600_i2c_bus *i2c_bus)
/* Clear Interrupt */
writel(GENMASK(27, 0), i2c_bus->reg_base + AST2600_I2CM_ISR);

+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+ /* for memory buffer initial */
+ if (i2c_bus->dma_available) {
+ i2c_bus->target_dma_buf =
+ dmam_alloc_coherent(i2c_bus->dev, I2C_TARGET_MSG_BUF_SIZE,
+ &i2c_bus->target_dma_addr, GFP_KERNEL);
+ if (!i2c_bus->target_dma_buf)
+ return -ENOMEM;
+ }
+
+ writel(GENMASK(27, 0), i2c_bus->reg_base + AST2600_I2CS_ISR);
+
+ if (i2c_bus->mode == BYTE_MODE)
+ writel(GENMASK(15, 0), i2c_bus->reg_base + AST2600_I2CS_IER);
+ else
+ writel(AST2600_I2CS_PKT_DONE, i2c_bus->reg_base + AST2600_I2CS_IER);
+#endif
+
+ return 0;
+}
+
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+static int ast2600_i2c_reg_target(struct i2c_client *client)
+{
+ struct ast2600_i2c_bus *i2c_bus = i2c_get_adapdata(client->adapter);
+ u32 cmd = TARGET_TRIGGER_CMD;
+
+ if (i2c_bus->target)
+ return -EINVAL;
+
+ dev_dbg(i2c_bus->dev, "target addr %x\n", client->addr);
+
+ writel(0, i2c_bus->reg_base + AST2600_I2CS_ADDR_CTRL);
+ writel(AST2600_I2CC_SLAVE_EN | readl(i2c_bus->reg_base + AST2600_I2CC_FUN_CTRL),
+ i2c_bus->reg_base + AST2600_I2CC_FUN_CTRL);
+
+ /* trigger rx buffer */
+ if (i2c_bus->mode == DMA_MODE) {
+ cmd |= AST2600_I2CS_RX_DMA_EN;
+ writel(i2c_bus->target_dma_addr, i2c_bus->reg_base + AST2600_I2CS_RX_DMA);
+ writel(i2c_bus->target_dma_addr, i2c_bus->reg_base + AST2600_I2CS_TX_DMA);
+ writel(AST2600_I2CS_SET_RX_DMA_LEN(I2C_TARGET_MSG_BUF_SIZE),
+ i2c_bus->reg_base + AST2600_I2CS_DMA_LEN);
+ } else if (i2c_bus->mode == BUFF_MODE) {
+ cmd = TARGET_TRIGGER_CMD;
+ } else {
+ cmd &= ~AST2600_I2CS_PKT_MODE_EN;
+ }
+
+ writel(cmd, i2c_bus->reg_base + AST2600_I2CS_CMD_STS);
+ i2c_bus->target = client;
+ /* Set target addr. */
+ writel(client->addr | AST2600_I2CS_ADDR1_ENABLE,
+ i2c_bus->reg_base + AST2600_I2CS_ADDR_CTRL);
+
+ return 0;
+}
+
+static int ast2600_i2c_unreg_target(struct i2c_client *client)
+{
+ struct ast2600_i2c_bus *i2c_bus = i2c_get_adapdata(client->adapter);
+ u32 val;
+
+ /* Turn off target mode. */
+ val = readl(i2c_bus->reg_base + AST2600_I2CC_FUN_CTRL);
+ writel(val & ~AST2600_I2CC_SLAVE_EN, i2c_bus->reg_base + AST2600_I2CC_FUN_CTRL);
+ val = readl(i2c_bus->reg_base + AST2600_I2CS_ADDR_CTRL);
+ writel(val & ~AST2600_I2CS_ADDR1_MASK, i2c_bus->reg_base + AST2600_I2CS_ADDR_CTRL);
+
+ i2c_bus->target = NULL;
+
return 0;
}
+#endif

static u32 ast2600_i2c_functionality(struct i2c_adapter *adap)
{
@@ -825,6 +1384,10 @@ static u32 ast2600_i2c_functionality(struct i2c_adapter *adap)
static const struct i2c_algorithm i2c_ast2600_algorithm = {
.xfer = ast2600_i2c_controller_xfer,
.functionality = ast2600_i2c_functionality,
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+ .reg_target = ast2600_i2c_reg_target,
+ .unreg_target = ast2600_i2c_unreg_target,
+#endif
};

static void ast2600_i2c_set_xfer_mode(struct ast2600_i2c_bus *i2c_bus,
@@ -960,6 +1523,9 @@ static int ast2600_i2c_probe(struct platform_device *pdev)
regmap_write(i2c_bus->global_regs, AST2600_I2CG_CLK_DIV_CTRL, I2CCG_DIV_CTRL);
}

+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+ WRITE_ONCE(i2c_bus->target_active, false);
+#endif
i2c_bus->dev = dev;
i2c_bus->multi_master = device_property_read_bool(dev, "multi-master");
i2c_bus->dma_available = device_property_read_bool(dev, "aspeed,enable-dma");

--
2.34.1