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Subject[PATCH v13 3/3] i2c: npcm7xx: Add support for slave mode for Nuvoton
Date
Add support for slave mode for Nuvoton
NPCM BMC I2C controller driver.

Signed-off-by: Tali Perry <tali.perry1@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
drivers/i2c/busses/i2c-npcm7xx.c | 609 ++++++++++++++++++++++++++++++-
1 file changed, 608 insertions(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-npcm7xx.c b/drivers/i2c/busses/i2c-npcm7xx.c
index c6e512908fa2..579985f0a6f2 100644
--- a/drivers/i2c/busses/i2c-npcm7xx.c
+++ b/drivers/i2c/busses/i2c-npcm7xx.c
@@ -71,6 +71,24 @@ enum i2c_state {
I2C_STOP_PENDING,
};

+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+/* Module supports setting multiple own slave addresses */
+enum i2c_addr {
+ I2C_SLAVE_ADDR1 = 0,
+ I2C_SLAVE_ADDR2,
+ I2C_SLAVE_ADDR3,
+ I2C_SLAVE_ADDR4,
+ I2C_SLAVE_ADDR5,
+ I2C_SLAVE_ADDR6,
+ I2C_SLAVE_ADDR7,
+ I2C_SLAVE_ADDR8,
+ I2C_SLAVE_ADDR9,
+ I2C_SLAVE_ADDR10,
+ I2C_GC_ADDR,
+ I2C_ARP_ADDR,
+};
+#endif
+
/* init register and default value required to enable module */
#define NPCM_I2CSEGCTL 0xE4
#define NPCM_I2CSEGCTL_INIT_VAL 0x0333F000
@@ -98,6 +116,23 @@ enum i2c_state {
#define NPCM_I2CADDR6 0x16
#define NPCM_I2CADDR10 0x17

+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+/*
+ * npcm_i2caddr array:
+ * The module supports having multiple own slave addresses.
+ * Since the addr regs are sprinkled all over the address space,
+ * use this array to get the address or each register.
+ */
+#define I2C_NUM_OWN_ADDR 10
+const int npcm_i2caddr[I2C_NUM_OWN_ADDR] = {
+ NPCM_I2CADDR1, NPCM_I2CADDR2,
+ NPCM_I2CADDR3, NPCM_I2CADDR4,
+ NPCM_I2CADDR5, NPCM_I2CADDR6,
+ NPCM_I2CADDR7, NPCM_I2CADDR8,
+ NPCM_I2CADDR9, NPCM_I2CADDR10,
+ };
+#endif
+
#define NPCM_I2CCTL4 0x1A
#define NPCM_I2CCTL5 0x1B
#define NPCM_I2CSCLLT 0x1C /* SCL Low Time */
@@ -269,6 +304,16 @@ struct npcm_i2c {
unsigned long int_time_stamp;
unsigned long bus_freq; /* in kHz */
u32 xmits;
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+ u8 own_slave_addr;
+ struct i2c_client *slave;
+ int slv_rd_size;
+ int slv_rd_ind;
+ int slv_wr_size;
+ int slv_wr_ind;
+ u8 slv_rd_buf[I2C_HW_FIFO_SIZE];
+ u8 slv_wr_buf[I2C_HW_FIFO_SIZE];
+#endif
struct dentry *debugfs; /* debugfs device directory */
u64 ber_cnt;
u64 rec_succ_cnt;
@@ -301,6 +346,10 @@ static void npcm_i2c_init_params(struct npcm_i2c *bus)
bus->int_time_stamp = 0;
bus->PEC_use = false;
bus->PEC_mask = 0;
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+ if (bus->slave)
+ bus->master_or_slave = I2C_SLAVE;
+#endif
}

static inline void npcm_i2c_wr_byte(struct npcm_i2c *bus, u8 data)
@@ -346,6 +395,18 @@ static void npcm_i2c_disable(struct npcm_i2c *bus)
{
u8 i2cctl2;

+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+ int i;
+
+ /* select bank 0 for I2C addresses */
+ npcm_i2c_select_bank(bus, I2C_BANK_0);
+
+ /* Slave addresses removal */
+ for (i = I2C_SLAVE_ADDR1; i < I2C_NUM_OWN_ADDR; i++)
+ iowrite8(0, bus->reg + npcm_i2caddr[i]);
+
+ npcm_i2c_select_bank(bus, I2C_BANK_1);
+#endif
/* Disable module */
i2cctl2 = ioread8(bus->reg + NPCM_I2CCTL2);
i2cctl2 = i2cctl2 & ~I2CCTL2_ENABLE;
@@ -509,6 +570,61 @@ static inline void npcm_i2c_nack(struct npcm_i2c *bus)
iowrite8(val, bus->reg + NPCM_I2CCTL1);
}

+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+static void npcm_i2c_slave_int_enable(struct npcm_i2c *bus, bool enable)
+{
+ u8 i2cctl1;
+
+ /* enable interrupt on slave match: */
+ i2cctl1 = ioread8(bus->reg + NPCM_I2CCTL1);
+ i2cctl1 &= ~NPCM_I2CCTL1_RWS;
+ if (enable)
+ i2cctl1 |= NPCM_I2CCTL1_NMINTE;
+ else
+ i2cctl1 &= ~NPCM_I2CCTL1_NMINTE;
+ iowrite8(i2cctl1, bus->reg + NPCM_I2CCTL1);
+}
+
+static int npcm_i2c_slave_enable(struct npcm_i2c *bus, enum i2c_addr addr_type,
+ u8 addr, bool enable)
+{
+ u8 i2cctl1;
+ u8 i2cctl3;
+ u8 sa_reg;
+
+ sa_reg = (addr & 0x7F) | FIELD_PREP(NPCM_I2CADDR_SAEN, enable);
+ if (addr_type == I2C_GC_ADDR) {
+ i2cctl1 = ioread8(bus->reg + NPCM_I2CCTL1);
+ if (enable)
+ i2cctl1 |= NPCM_I2CCTL1_GCMEN;
+ else
+ i2cctl1 &= ~NPCM_I2CCTL1_GCMEN;
+ iowrite8(i2cctl1, bus->reg + NPCM_I2CCTL1);
+ return 0;
+ }
+ if (addr_type == I2C_ARP_ADDR) {
+ i2cctl3 = ioread8(bus->reg + NPCM_I2CCTL3);
+ if (enable)
+ i2cctl3 |= I2CCTL3_ARPMEN;
+ else
+ i2cctl3 &= ~I2CCTL3_ARPMEN;
+ iowrite8(i2cctl3, bus->reg + NPCM_I2CCTL3);
+ return 0;
+ }
+ if (addr_type >= I2C_ARP_ADDR)
+ return -EFAULT;
+ /* select bank 0 for address 3 to 10 */
+ if (addr_type > I2C_SLAVE_ADDR2)
+ npcm_i2c_select_bank(bus, I2C_BANK_0);
+ /* Set and enable the address */
+ iowrite8(sa_reg, bus->reg + npcm_i2caddr[(int)addr_type]);
+ npcm_i2c_slave_int_enable(bus, enable);
+ if (addr_type > I2C_SLAVE_ADDR2)
+ npcm_i2c_select_bank(bus, I2C_BANK_1);
+ return 0;
+}
+#endif
+
static void npcm_i2c_reset(struct npcm_i2c *bus)
{
/*
@@ -517,6 +633,7 @@ static void npcm_i2c_reset(struct npcm_i2c *bus)
*/
u8 i2cctl1;
u8 i2cctl2;
+ u8 addr;

i2cctl1 = ioread8(bus->reg + NPCM_I2CCTL1);
i2cctl2 = ioread8(bus->reg + NPCM_I2CCTL2);
@@ -538,6 +655,13 @@ static void npcm_i2c_reset(struct npcm_i2c *bus)
/* Clear all fifo bits: */
iowrite8(NPCM_I2CFIF_CTS_CLR_FIFO, bus->reg + NPCM_I2CFIF_CTS);

+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+ if (bus->slave) {
+ addr = bus->slave->addr;
+ npcm_i2c_slave_enable(bus, I2C_SLAVE_ADDR1, addr, true);
+ }
+#endif
+
bus->state = I2C_IDLE;
}

@@ -603,6 +727,10 @@ static void npcm_i2c_callback(struct npcm_i2c *bus,
}

bus->operation = I2C_NO_OPER;
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+ if (bus->slave)
+ bus->master_or_slave = I2C_SLAVE;
+#endif
}

static u8 npcm_i2c_fifo_usage(struct npcm_i2c *bus)
@@ -714,6 +842,460 @@ static void npcm_i2c_master_abort(struct npcm_i2c *bus)
npcm_i2c_clear_master_status(bus);
}

+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+static u8 npcm_i2c_get_slave_addr(struct npcm_i2c *bus, enum i2c_addr addr_type)
+{
+ u8 slave_add;
+
+ /* select bank 0 for address 3 to 10 */
+ if (addr_type > I2C_SLAVE_ADDR2)
+ npcm_i2c_select_bank(bus, I2C_BANK_0);
+
+ slave_add = ioread8(bus->reg + npcm_i2caddr[(int)addr_type]);
+
+ if (addr_type > I2C_SLAVE_ADDR2)
+ npcm_i2c_select_bank(bus, I2C_BANK_1);
+
+ return slave_add;
+}
+
+static int npcm_i2c_remove_slave_addr(struct npcm_i2c *bus, u8 slave_add)
+{
+ int i;
+
+ /* Set the enable bit */
+ slave_add |= 0x80;
+ npcm_i2c_select_bank(bus, I2C_BANK_0);
+ for (i = I2C_SLAVE_ADDR1; i < I2C_NUM_OWN_ADDR; i++) {
+ if (ioread8(bus->reg + npcm_i2caddr[i]) == slave_add)
+ iowrite8(0, bus->reg + npcm_i2caddr[i]);
+ }
+ npcm_i2c_select_bank(bus, I2C_BANK_1);
+ return 0;
+}
+
+static void npcm_i2c_write_fifo_slave(struct npcm_i2c *bus, u16 max_bytes)
+{
+ /*
+ * Fill the FIFO, while the FIFO is not full and there are more bytes
+ * to write
+ */
+ npcm_i2c_clear_fifo_int(bus);
+ npcm_i2c_clear_tx_fifo(bus);
+ iowrite8(0, bus->reg + NPCM_I2CTXF_CTL);
+ while (max_bytes-- && I2C_HW_FIFO_SIZE != npcm_i2c_fifo_usage(bus)) {
+ if (bus->slv_wr_size <= 0)
+ break;
+ bus->slv_wr_ind = bus->slv_wr_ind % I2C_HW_FIFO_SIZE;
+ npcm_i2c_wr_byte(bus, bus->slv_wr_buf[bus->slv_wr_ind]);
+ bus->slv_wr_ind++;
+ bus->slv_wr_ind = bus->slv_wr_ind % I2C_HW_FIFO_SIZE;
+ bus->slv_wr_size--;
+ }
+}
+
+static void npcm_i2c_read_fifo_slave(struct npcm_i2c *bus, u8 bytes_in_fifo)
+{
+ u8 data;
+
+ if (!bus->slave)
+ return;
+
+ while (bytes_in_fifo--) {
+ data = npcm_i2c_rd_byte(bus);
+
+ bus->slv_rd_ind = bus->slv_rd_ind % I2C_HW_FIFO_SIZE;
+ bus->slv_rd_buf[bus->slv_rd_ind] = data;
+ bus->slv_rd_ind++;
+
+ /* 1st byte is length in block protocol: */
+ if (bus->slv_rd_ind == 1 && bus->read_block_use)
+ bus->slv_rd_size = data + bus->PEC_use + 1;
+ }
+}
+
+static int npcm_i2c_slave_get_wr_buf(struct npcm_i2c *bus)
+{
+ int i;
+ u8 value;
+ int ind;
+ int ret = bus->slv_wr_ind;
+
+ /* fill a cyclic buffer */
+ for (i = 0; i < I2C_HW_FIFO_SIZE; i++) {
+ if (bus->slv_wr_size >= I2C_HW_FIFO_SIZE)
+ break;
+ i2c_slave_event(bus->slave, I2C_SLAVE_READ_REQUESTED, &value);
+ ind = (bus->slv_wr_ind + bus->slv_wr_size) % I2C_HW_FIFO_SIZE;
+ bus->slv_wr_buf[ind] = value;
+ bus->slv_wr_size++;
+ i2c_slave_event(bus->slave, I2C_SLAVE_READ_PROCESSED, &value);
+ }
+ return I2C_HW_FIFO_SIZE - ret;
+}
+
+static void npcm_i2c_slave_send_rd_buf(struct npcm_i2c *bus)
+{
+ int i;
+
+ for (i = 0; i < bus->slv_rd_ind; i++)
+ i2c_slave_event(bus->slave, I2C_SLAVE_WRITE_RECEIVED,
+ &bus->slv_rd_buf[i]);
+ /*
+ * once we send bytes up, need to reset the counter of the wr buf
+ * got data from master (new offset in device), ignore wr fifo:
+ */
+ if (bus->slv_rd_ind) {
+ bus->slv_wr_size = 0;
+ bus->slv_wr_ind = 0;
+ }
+
+ bus->slv_rd_ind = 0;
+ bus->slv_rd_size = bus->adap.quirks->max_read_len;
+
+ npcm_i2c_clear_fifo_int(bus);
+ npcm_i2c_clear_rx_fifo(bus);
+}
+
+static void npcm_i2c_slave_receive(struct npcm_i2c *bus, u16 nread,
+ u8 *read_data)
+{
+ bus->state = I2C_OPER_STARTED;
+ bus->operation = I2C_READ_OPER;
+ bus->slv_rd_size = nread;
+ bus->slv_rd_ind = 0;
+
+ iowrite8(0, bus->reg + NPCM_I2CTXF_CTL);
+ iowrite8(I2C_HW_FIFO_SIZE, bus->reg + NPCM_I2CRXF_CTL);
+ npcm_i2c_clear_tx_fifo(bus);
+ npcm_i2c_clear_rx_fifo(bus);
+}
+
+static void npcm_i2c_slave_xmit(struct npcm_i2c *bus, u16 nwrite,
+ u8 *write_data)
+{
+ if (nwrite == 0)
+ return;
+
+ bus->state = I2C_OPER_STARTED;
+ bus->operation = I2C_WRITE_OPER;
+
+ /* get the next buffer */
+ npcm_i2c_slave_get_wr_buf(bus);
+ npcm_i2c_write_fifo_slave(bus, nwrite);
+}
+
+/*
+ * npcm_i2c_slave_wr_buf_sync:
+ * currently slave IF only supports single byte operations.
+ * in order to utilyze the npcm HW FIFO, the driver will ask for 16 bytes
+ * at a time, pack them in buffer, and then transmit them all together
+ * to the FIFO and onward to the bus.
+ * NACK on read will be once reached to bus->adap->quirks->max_read_len.
+ * sending a NACK wherever the backend requests for it is not supported.
+ * the next two functions allow reading to local buffer before writing it all
+ * to the HW FIFO.
+ */
+static void npcm_i2c_slave_wr_buf_sync(struct npcm_i2c *bus)
+{
+ int left_in_fifo;
+
+ left_in_fifo = FIELD_GET(NPCM_I2CTXF_STS_TX_BYTES,
+ ioread8(bus->reg + NPCM_I2CTXF_STS));
+
+ /* fifo already full: */
+ if (left_in_fifo >= I2C_HW_FIFO_SIZE ||
+ bus->slv_wr_size >= I2C_HW_FIFO_SIZE)
+ return;
+
+ /* update the wr fifo index back to the untransmitted bytes: */
+ bus->slv_wr_ind = bus->slv_wr_ind - left_in_fifo;
+ bus->slv_wr_size = bus->slv_wr_size + left_in_fifo;
+
+ if (bus->slv_wr_ind < 0)
+ bus->slv_wr_ind += I2C_HW_FIFO_SIZE;
+}
+
+static void npcm_i2c_slave_rd_wr(struct npcm_i2c *bus)
+{
+ if (NPCM_I2CST_XMIT & ioread8(bus->reg + NPCM_I2CST)) {
+ /*
+ * Slave got an address match with direction bit 1 so it should
+ * transmit data. Write till the master will NACK
+ */
+ bus->operation = I2C_WRITE_OPER;
+ npcm_i2c_slave_xmit(bus, bus->adap.quirks->max_write_len,
+ bus->slv_wr_buf);
+ } else {
+ /*
+ * Slave got an address match with direction bit 0 so it should
+ * receive data.
+ * this module does not support saying no to bytes.
+ * it will always ACK.
+ */
+ bus->operation = I2C_READ_OPER;
+ npcm_i2c_read_fifo_slave(bus, npcm_i2c_fifo_usage(bus));
+ bus->stop_ind = I2C_SLAVE_RCV_IND;
+ npcm_i2c_slave_send_rd_buf(bus);
+ npcm_i2c_slave_receive(bus, bus->adap.quirks->max_read_len,
+ bus->slv_rd_buf);
+ }
+}
+
+static irqreturn_t npcm_i2c_int_slave_handler(struct npcm_i2c *bus)
+{
+ u8 val;
+ irqreturn_t ret = IRQ_NONE;
+ u8 i2cst = ioread8(bus->reg + NPCM_I2CST);
+
+ /* Slave: A NACK has occurred */
+ if (NPCM_I2CST_NEGACK & i2cst) {
+ bus->stop_ind = I2C_NACK_IND;
+ npcm_i2c_slave_wr_buf_sync(bus);
+ if (bus->fifo_use)
+ /* clear the FIFO */
+ iowrite8(NPCM_I2CFIF_CTS_CLR_FIFO,
+ bus->reg + NPCM_I2CFIF_CTS);
+
+ /* In slave write, NACK is OK, otherwise it is a problem */
+ bus->stop_ind = I2C_NO_STATUS_IND;
+ bus->operation = I2C_NO_OPER;
+ bus->own_slave_addr = 0xFF;
+
+ /*
+ * Slave has to wait for STOP to decide this is the end
+ * of the transaction. tx is not yet considered as done
+ */
+ iowrite8(NPCM_I2CST_NEGACK, bus->reg + NPCM_I2CST);
+
+ ret = IRQ_HANDLED;
+ }
+
+ /* Slave mode: a Bus Error (BER) has been identified */
+ if (NPCM_I2CST_BER & i2cst) {
+ /*
+ * Check whether bus arbitration or Start or Stop during data
+ * xfer bus arbitration problem should not result in recovery
+ */
+ bus->stop_ind = I2C_BUS_ERR_IND;
+
+ /* wait for bus busy before clear fifo */
+ iowrite8(NPCM_I2CFIF_CTS_CLR_FIFO, bus->reg + NPCM_I2CFIF_CTS);
+
+ bus->state = I2C_IDLE;
+
+ /*
+ * in BER case we might get 2 interrupts: one for slave one for
+ * master ( for a channel which is master\slave switching)
+ */
+ if (completion_done(&bus->cmd_complete) == false) {
+ bus->cmd_err = -EIO;
+ complete(&bus->cmd_complete);
+ }
+ bus->own_slave_addr = 0xFF;
+ iowrite8(NPCM_I2CST_BER, bus->reg + NPCM_I2CST);
+ ret = IRQ_HANDLED;
+ }
+
+ /* A Slave Stop Condition has been identified */
+ if (NPCM_I2CST_SLVSTP & i2cst) {
+ u8 bytes_in_fifo = npcm_i2c_fifo_usage(bus);
+
+ bus->stop_ind = I2C_SLAVE_DONE_IND;
+
+ if (bus->operation == I2C_READ_OPER)
+ npcm_i2c_read_fifo_slave(bus, bytes_in_fifo);
+
+ /* if the buffer is empty nothing will be sent */
+ npcm_i2c_slave_send_rd_buf(bus);
+
+ /* Slave done transmitting or receiving */
+ bus->stop_ind = I2C_NO_STATUS_IND;
+
+ /*
+ * Note, just because we got here, it doesn't mean we through
+ * away the wr buffer.
+ * we keep it until the next received offset.
+ */
+ bus->operation = I2C_NO_OPER;
+ bus->int_cnt = 0;
+ bus->own_slave_addr = 0xFF;
+ i2c_slave_event(bus->slave, I2C_SLAVE_STOP, 0);
+ iowrite8(NPCM_I2CST_SLVSTP, bus->reg + NPCM_I2CST);
+ if (bus->fifo_use) {
+ npcm_i2c_clear_fifo_int(bus);
+ npcm_i2c_clear_rx_fifo(bus);
+ npcm_i2c_clear_tx_fifo(bus);
+
+ iowrite8(NPCM_I2CFIF_CTS_CLR_FIFO,
+ bus->reg + NPCM_I2CFIF_CTS);
+ }
+ bus->state = I2C_IDLE;
+ ret = IRQ_HANDLED;
+ }
+
+ /* restart condition occurred and Rx-FIFO was not empty */
+ if (bus->fifo_use && FIELD_GET(NPCM_I2CFIF_CTS_SLVRSTR,
+ ioread8(bus->reg + NPCM_I2CFIF_CTS))) {
+ bus->stop_ind = I2C_SLAVE_RESTART_IND;
+ bus->master_or_slave = I2C_SLAVE;
+ if (bus->operation == I2C_READ_OPER)
+ npcm_i2c_read_fifo_slave(bus, npcm_i2c_fifo_usage(bus));
+ bus->operation = I2C_WRITE_OPER;
+ iowrite8(0, bus->reg + NPCM_I2CRXF_CTL);
+ val = NPCM_I2CFIF_CTS_CLR_FIFO | NPCM_I2CFIF_CTS_SLVRSTR |
+ NPCM_I2CFIF_CTS_RXF_TXE;
+ iowrite8(val, bus->reg + NPCM_I2CFIF_CTS);
+ npcm_i2c_slave_rd_wr(bus);
+ ret = IRQ_HANDLED;
+ }
+
+ /* A Slave Address Match has been identified */
+ if (NPCM_I2CST_NMATCH & i2cst) {
+ u8 info = 0;
+
+ /* Address match automatically implies slave mode */
+ bus->master_or_slave = I2C_SLAVE;
+ npcm_i2c_clear_fifo_int(bus);
+ npcm_i2c_clear_rx_fifo(bus);
+ npcm_i2c_clear_tx_fifo(bus);
+ iowrite8(0, bus->reg + NPCM_I2CTXF_CTL);
+ iowrite8(I2C_HW_FIFO_SIZE, bus->reg + NPCM_I2CRXF_CTL);
+ if (NPCM_I2CST_XMIT & i2cst) {
+ bus->operation = I2C_WRITE_OPER;
+ } else {
+ i2c_slave_event(bus->slave, I2C_SLAVE_WRITE_REQUESTED,
+ &info);
+ bus->operation = I2C_READ_OPER;
+ }
+ if (bus->own_slave_addr == 0xFF) {
+ /* Check which type of address match */
+ val = ioread8(bus->reg + NPCM_I2CCST);
+ if (NPCM_I2CCST_MATCH & val) {
+ u16 addr;
+ enum i2c_addr eaddr;
+ u8 i2ccst2;
+ u8 i2ccst3;
+
+ i2ccst3 = ioread8(bus->reg + NPCM_I2CCST3);
+ i2ccst2 = ioread8(bus->reg + NPCM_I2CCST2);
+
+ /*
+ * the i2c module can response to 10 own SA.
+ * check which one was addressed by the master.
+ * repond to the first one.
+ */
+ addr = ((i2ccst3 & 0x07) << 7) |
+ (i2ccst2 & 0x7F);
+ info = ffs(addr);
+ eaddr = (enum i2c_addr)info;
+ addr = npcm_i2c_get_slave_addr(bus, eaddr);
+ addr &= 0x7F;
+ bus->own_slave_addr = addr;
+ if (bus->PEC_mask & BIT(info))
+ bus->PEC_use = true;
+ else
+ bus->PEC_use = false;
+ } else {
+ if (NPCM_I2CCST_GCMATCH & val)
+ bus->own_slave_addr = 0;
+ if (NPCM_I2CCST_ARPMATCH & val)
+ bus->own_slave_addr = 0x61;
+ }
+ } else {
+ /*
+ * Slave match can happen in two options:
+ * 1. Start, SA, read (slave read without further ado)
+ * 2. Start, SA, read, data, restart, SA, read, ...
+ * (slave read in fragmented mode)
+ * 3. Start, SA, write, data, restart, SA, read, ..
+ * (regular write-read mode)
+ */
+ if ((bus->state == I2C_OPER_STARTED &&
+ bus->operation == I2C_READ_OPER &&
+ bus->stop_ind == I2C_SLAVE_XMIT_IND) ||
+ bus->stop_ind == I2C_SLAVE_RCV_IND) {
+ /* slave tx after slave rx w/o STOP */
+ bus->stop_ind = I2C_SLAVE_RESTART_IND;
+ }
+ }
+
+ if (NPCM_I2CST_XMIT & i2cst)
+ bus->stop_ind = I2C_SLAVE_XMIT_IND;
+ else
+ bus->stop_ind = I2C_SLAVE_RCV_IND;
+ bus->state = I2C_SLAVE_MATCH;
+ npcm_i2c_slave_rd_wr(bus);
+ iowrite8(NPCM_I2CST_NMATCH, bus->reg + NPCM_I2CST);
+ ret = IRQ_HANDLED;
+ }
+
+ /* Slave SDA status is set - tx or rx */
+ if ((NPCM_I2CST_SDAST & i2cst) ||
+ (bus->fifo_use &&
+ (npcm_i2c_tx_fifo_empty(bus) || npcm_i2c_rx_fifo_full(bus)))) {
+ npcm_i2c_slave_rd_wr(bus);
+ iowrite8(NPCM_I2CST_SDAST, bus->reg + NPCM_I2CST);
+ ret = IRQ_HANDLED;
+ } /* SDAST */
+
+ return ret;
+}
+
+static int npcm_i2c_reg_slave(struct i2c_client *client)
+{
+ unsigned long lock_flags;
+ struct npcm_i2c *bus = i2c_get_adapdata(client->adapter);
+
+ bus->slave = client;
+
+ if (!bus->slave)
+ return -EINVAL;
+
+ if (client->flags & I2C_CLIENT_TEN)
+ return -EAFNOSUPPORT;
+
+ spin_lock_irqsave(&bus->lock, lock_flags);
+
+ npcm_i2c_init_params(bus);
+ bus->slv_rd_size = 0;
+ bus->slv_wr_size = 0;
+ bus->slv_rd_ind = 0;
+ bus->slv_wr_ind = 0;
+ if (client->flags & I2C_CLIENT_PEC)
+ bus->PEC_use = true;
+
+ dev_info(bus->dev, "i2c%d register slave SA=0x%x, PEC=%d\n", bus->num,
+ client->addr, bus->PEC_use);
+
+ npcm_i2c_slave_enable(bus, I2C_SLAVE_ADDR1, client->addr, true);
+ npcm_i2c_clear_fifo_int(bus);
+ npcm_i2c_clear_rx_fifo(bus);
+ npcm_i2c_clear_tx_fifo(bus);
+ npcm_i2c_slave_int_enable(bus, true);
+
+ spin_unlock_irqrestore(&bus->lock, lock_flags);
+ return 0;
+}
+
+static int npcm_i2c_unreg_slave(struct i2c_client *client)
+{
+ struct npcm_i2c *bus = client->adapter->algo_data;
+ unsigned long lock_flags;
+
+ spin_lock_irqsave(&bus->lock, lock_flags);
+ if (!bus->slave) {
+ spin_unlock_irqrestore(&bus->lock, lock_flags);
+ return -EINVAL;
+ }
+ npcm_i2c_slave_int_enable(bus, false);
+ npcm_i2c_remove_slave_addr(bus, client->addr);
+ bus->slave = NULL;
+ spin_unlock_irqrestore(&bus->lock, lock_flags);
+ return 0;
+}
+#endif /* CONFIG_I2C_SLAVE */
+
static void npcm_i2c_master_fifo_read(struct npcm_i2c *bus)
{
int rcount;
@@ -1399,6 +1981,9 @@ static int __npcm_i2c_init(struct npcm_i2c *bus, struct platform_device *pdev)
bus->master_or_slave = I2C_SLAVE;
bus->int_time_stamp = 0;
bus->xmits = 0;
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+ bus->slave = NULL;
+#endif

ret = device_property_read_u32(&pdev->dev, "bus-frequency",
&clk_freq_hz);
@@ -1429,6 +2014,12 @@ static irqreturn_t npcm_i2c_bus_irq(int irq, void *dev_id)
if (!npcm_i2c_int_master_handler(bus))
return IRQ_HANDLED;
}
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+ if (bus->slave) {
+ bus->master_or_slave = I2C_SLAVE;
+ return npcm_i2c_int_slave_handler(bus);
+ }
+#endif
return IRQ_NONE;
}

@@ -1570,6 +2161,11 @@ static int npcm_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
*/
spin_lock_irqsave(&bus->lock, flags);
bus_busy = ioread8(bus->reg + NPCM_I2CCST) & NPCM_I2CCST_BB;
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+ if (!bus_busy && bus->slave)
+ iowrite8((bus->slave->addr & 0x7F),
+ bus->reg + NPCM_I2CADDR1);
+#endif
spin_unlock_irqrestore(&bus->lock, flags);

} while (time_is_after_jiffies(time_left) && bus_busy);
@@ -1620,6 +2216,12 @@ static int npcm_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
if (bus->cmd_err == -EAGAIN)
ret = i2c_recover_bus(adap);

+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+ /* reenable slave if it was enabled */
+ if (bus->slave)
+ iowrite8((bus->slave->addr & 0x7F) | NPCM_I2CADDR_SAEN,
+ bus->reg + NPCM_I2CADDR1);
+#endif
return bus->cmd_err;
}

@@ -1628,7 +2230,8 @@ static u32 npcm_i2c_functionality(struct i2c_adapter *adap)
return I2C_FUNC_I2C |
I2C_FUNC_SMBUS_EMUL |
I2C_FUNC_SMBUS_BLOCK_DATA |
- I2C_FUNC_SMBUS_PEC;
+ I2C_FUNC_SMBUS_PEC |
+ I2C_FUNC_SLAVE;
}

static const struct i2c_adapter_quirks npcm_i2c_quirks = {
@@ -1641,6 +2244,10 @@ static const struct i2c_adapter_quirks npcm_i2c_quirks = {
static const struct i2c_algorithm npcm_i2c_algo = {
.master_xfer = npcm_i2c_master_xfer,
.functionality = npcm_i2c_functionality,
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+ .reg_slave = npcm_i2c_reg_slave,
+ .unreg_slave = npcm_i2c_unreg_slave,
+#endif
};

/* i2c debugfs directory: used to keep health monitor of i2c devices */
--
2.22.0
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