Re: [PATCH] i2c: cadence: Added slave support

Michal Simek
2019-12-20T09:17:17Z

On 19. 12. 19 13:41, Radu Pirea wrote:
> Added support for I2C slave functionality
>
> Signed-off-by: Chirag Parekh <chirag.parekh@xilinx.com>
> Signed-off-by: Michal Simek <michal.simek@xilinx.com>
> Signed-off-by: Radu Pirea <radu_nicolae.pirea@upb.ro>
> ---
>
> Hi,
>
> This patch implements the slave interface for the i2c cadence driver. Most of the
> work has been done by the guys from Xilinx. All I have done it was to port the
> patch to the upstream kernel, test it and fix some minor issues.
>
> Any suggestion about how can I improve this patch is welcome.
>
> Thanks.
>
> Radu P.
>
> drivers/i2c/busses/i2c-cadence.c | 317 ++++++++++++++++++++++++++++++-
> 1 file changed, 307 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-cadence.c b/drivers/i2c/busses/i2c-cadence.c
> index 9d71ce15db05..ea6bf989ba1c 100644
> --- a/drivers/i2c/busses/i2c-cadence.c
> +++ b/drivers/i2c/busses/i2c-cadence.c
> @@ -23,6 +23,7 @@
> #define CDNS_I2C_ISR_OFFSET 0x10 /* IRQ Status Register, RW */
> #define CDNS_I2C_XFER_SIZE_OFFSET 0x14 /* Transfer Size Register, RW */
> #define CDNS_I2C_TIME_OUT_OFFSET 0x1C /* Time Out Register, RW */
> +#define CDNS_I2C_IMR_OFFSET 0x20 /* IRQ Mask Register, RO */
> #define CDNS_I2C_IER_OFFSET 0x24 /* IRQ Enable Register, WO */
> #define CDNS_I2C_IDR_OFFSET 0x28 /* IRQ Disable Register, WO */
>
> @@ -40,9 +41,17 @@
> #define CDNS_I2C_CR_DIVB_SHIFT 8
> #define CDNS_I2C_CR_DIVB_MASK (0x3f << CDNS_I2C_CR_DIVB_SHIFT)
>
> +#define CDNS_I2C_CR_MASTER_EN_MASK (CDNS_I2C_CR_NEA | \
> + CDNS_I2C_CR_ACK_EN | \
> + CDNS_I2C_CR_MS)
> +
> +#define CDNS_I2C_CR_SLAVE_EN_MASK ~CDNS_I2C_CR_MASTER_EN_MASK
> +
> /* Status Register Bit mask definitions */
> #define CDNS_I2C_SR_BA BIT(8)
> +#define CDNS_I2C_SR_TXDV BIT(6)
> #define CDNS_I2C_SR_RXDV BIT(5)
> +#define CDNS_I2C_SR_RXRW BIT(3)
>
> /*
> * I2C Address Register Bit mask definitions
> @@ -91,6 +100,14 @@
> CDNS_I2C_IXR_DATA | \
> CDNS_I2C_IXR_COMP)
>
> +#define CDNS_I2C_IXR_SLAVE_INTR_MASK (CDNS_I2C_IXR_RX_UNF | \
> + CDNS_I2C_IXR_TX_OVF | \
> + CDNS_I2C_IXR_RX_OVF | \
> + CDNS_I2C_IXR_TO | \
> + CDNS_I2C_IXR_NACK | \
> + CDNS_I2C_IXR_DATA | \
> + CDNS_I2C_IXR_COMP)
> +
> #define CDNS_I2C_TIMEOUT msecs_to_jiffies(1000)
> /* timeout for pm runtime autosuspend */
> #define CNDS_I2C_PM_TIMEOUT 1000 /* ms */
> @@ -117,6 +134,32 @@
> #define cdns_i2c_readreg(offset) readl_relaxed(id->membase + offset)
> #define cdns_i2c_writereg(val, offset) writel_relaxed(val, id->membase + offset)
>
> +#if IS_ENABLED(CONFIG_I2C_SLAVE)
> +/**
> + * enum cdns_i2c_mode - I2C Controller current operating mode
> + *
> + * @CDNS_I2C_MODE_SLAVE: I2C controller operating in slave mode
> + * @CDNS_I2C_MODE_MASTER: I2C Controller operating in master mode
> + */
> +enum cdns_i2c_mode {
> + CDNS_I2C_MODE_SLAVE,
> + CDNS_I2C_MODE_MASTER,
> +};
> +
> +/**
> + * enum cdns_i2c_slave_mode - Slave state when I2C is operating in slave mode
> + *
> + * @CDNS_I2C_SLAVE_STATE_IDLE: I2C slave idle
> + * @CDNS_I2C_SLAVE_STATE_SEND: I2C slave sending data to master
> + * @CDNS_I2C_SLAVE_STATE_RECV: I2C slave receiving data from master
> + */
> +enum cdns_i2c_slave_state {
> + CDNS_I2C_SLAVE_STATE_IDLE,
> + CDNS_I2C_SLAVE_STATE_SEND,
> + CDNS_I2C_SLAVE_STATE_RECV,
> +};
> +#endif
> +
> /**
> * struct cdns_i2c - I2C device private data structure
> *
> @@ -138,6 +181,10 @@
> * @clk: Pointer to struct clk
> * @clk_rate_change_nb: Notifier block for clock rate changes
> * @quirks: flag for broken hold bit usage in r1p10
> + * @ctrl_reg_diva_divb: value of fields DIV_A and DIV_B from CR register
> + * @slave: Registered slave instance.
> + * @dev_mode: I2C operating role(master/slave).
> + * @slave_state: I2C Slave state(idle/read/write).
> */
> struct cdns_i2c {
> struct device *dev;
> @@ -158,6 +205,12 @@ struct cdns_i2c {
> struct clk *clk;
> struct notifier_block clk_rate_change_nb;
> u32 quirks;
> +#if IS_ENABLED(CONFIG_I2C_SLAVE)
> + u16 ctrl_reg_diva_divb;
> + struct i2c_client *slave;
> + enum cdns_i2c_mode dev_mode;
> + enum cdns_i2c_slave_state slave_state;
> +#endif
> };
>
> struct cdns_platform_data {
> @@ -186,17 +239,155 @@ static inline bool cdns_is_holdquirk(struct cdns_i2c *id, bool hold_wrkaround)
> (id->curr_recv_count == CDNS_I2C_FIFO_DEPTH + 1));
> }
>
> +#if IS_ENABLED(CONFIG_I2C_SLAVE)
> +static void cdns_i2c_set_mode(enum cdns_i2c_mode mode, struct cdns_i2c *id)
> +{
> + /* Disable all interrupts */
> + cdns_i2c_writereg(CDNS_I2C_IXR_ALL_INTR_MASK, CDNS_I2C_IDR_OFFSET);
> +
> + /* Clear FIFO and transfer size */
> + cdns_i2c_writereg(CDNS_I2C_CR_CLR_FIFO, CDNS_I2C_CR_OFFSET);
> +
> + /* Update device mode and state */
> + id->dev_mode = mode;
> + id->slave_state = CDNS_I2C_SLAVE_STATE_IDLE;
> +
> + switch (mode) {
> + case CDNS_I2C_MODE_MASTER:
> + /* Enable i2c master */
> + cdns_i2c_writereg(id->ctrl_reg_diva_divb |
> + CDNS_I2C_CR_MASTER_EN_MASK,
> + CDNS_I2C_CR_OFFSET);
> + /*
> + * This delay is needed to give the IP some time to switch to
> + * the master mode. With lower values(like 110 us) i2cdetect
> + * will not detect any slave and without this delay, the IP will
> + * trigger a timeout interrupt.
> + */
> + usleep_range(115, 125);
> + break;
> + case CDNS_I2C_MODE_SLAVE:
> + /* Enable i2c slave */
> + cdns_i2c_writereg(id->ctrl_reg_diva_divb &
> + CDNS_I2C_CR_SLAVE_EN_MASK,
> + CDNS_I2C_CR_OFFSET);
> +
> + /* Setting slave address */
> + cdns_i2c_writereg(id->slave->addr & CDNS_I2C_ADDR_MASK,
> + CDNS_I2C_ADDR_OFFSET);
> +
> + /* Enable slave send/receive interrupts */
> + cdns_i2c_writereg(CDNS_I2C_IXR_SLAVE_INTR_MASK,
> + CDNS_I2C_IER_OFFSET);
> + break;
> + }
> +}
> +
> +static void cdns_i2c_slave_rcv_data(struct cdns_i2c *id)
> +{
> + u8 bytes;
> + unsigned char data;
> +
> + /* Prepare backend for data reception */
> + if (id->slave_state == CDNS_I2C_SLAVE_STATE_IDLE) {
> + id->slave_state = CDNS_I2C_SLAVE_STATE_RECV;
> + i2c_slave_event(id->slave, I2C_SLAVE_WRITE_REQUESTED, NULL);
> + }
> +
> + /* Fetch number of bytes to receive */
> + bytes = cdns_i2c_readreg(CDNS_I2C_XFER_SIZE_OFFSET);
> +
> + /* Read data and send to backend */
> + while (bytes--) {
> + data = cdns_i2c_readreg(CDNS_I2C_DATA_OFFSET);
> + i2c_slave_event(id->slave, I2C_SLAVE_WRITE_RECEIVED, &data);
> + }
> +}
> +
> +static void cdns_i2c_slave_send_data(struct cdns_i2c *id)
> +{
> + u8 data;
> +
> + /* Prepare backend for data transmission */
> + if (id->slave_state == CDNS_I2C_SLAVE_STATE_IDLE) {
> + id->slave_state = CDNS_I2C_SLAVE_STATE_SEND;
> + i2c_slave_event(id->slave, I2C_SLAVE_READ_REQUESTED, &data);
> + } else {
> + i2c_slave_event(id->slave, I2C_SLAVE_READ_PROCESSED, &data);
> + }
> +
> + /* Send data over bus */
> + cdns_i2c_writereg(data, CDNS_I2C_DATA_OFFSET);
> +}
> +
> /**
> - * cdns_i2c_isr - Interrupt handler for the I2C device
> - * @irq: irq number for the I2C device
> - * @ptr: void pointer to cdns_i2c structure
> + * cdns_i2c_slave_isr - Interrupt handler for the I2C device in slave role
> + * @ptr: Pointer to I2C device private data
> + *
> + * This function handles the data interrupt and transfer complete interrupt of
> + * the I2C device in slave role.
> + *
> + * Return: IRQ_HANDLED always
> + */
> +static irqreturn_t cdns_i2c_slave_isr(void *ptr)
> +{
> + struct cdns_i2c *id = ptr;
> + unsigned int isr_status, i2c_status;
> +
> + /* Fetch the interrupt status */
> + isr_status = cdns_i2c_readreg(CDNS_I2C_ISR_OFFSET);
> + cdns_i2c_writereg(isr_status, CDNS_I2C_ISR_OFFSET);
> +
> + /* Ignore masked interrupts */
> + isr_status &= ~cdns_i2c_readreg(CDNS_I2C_IMR_OFFSET);
> +
> + /* Fetch transfer mode (send/receive) */
> + i2c_status = cdns_i2c_readreg(CDNS_I2C_SR_OFFSET);
> +
> + /* Handle data send/receive */
> + if (i2c_status & CDNS_I2C_SR_RXRW) {
> + /* Send data to master */
> + if (isr_status & CDNS_I2C_IXR_DATA)
> + cdns_i2c_slave_send_data(id);
> +
> + if (isr_status & CDNS_I2C_IXR_COMP) {
> + id->slave_state = CDNS_I2C_SLAVE_STATE_IDLE;
> + i2c_slave_event(id->slave, I2C_SLAVE_STOP, NULL);
> + }
> + } else {
> + /* Receive data from master */
> + if (isr_status & CDNS_I2C_IXR_DATA)
> + cdns_i2c_slave_rcv_data(id);
> +
> + if (isr_status & CDNS_I2C_IXR_COMP) {
> + cdns_i2c_slave_rcv_data(id);
> + id->slave_state = CDNS_I2C_SLAVE_STATE_IDLE;
> + i2c_slave_event(id->slave, I2C_SLAVE_STOP, NULL);
> + }
> + }
> +
> + /* Master indicated xfer stop or fifo underflow/overflow */
> + if (isr_status & (CDNS_I2C_IXR_NACK | CDNS_I2C_IXR_RX_OVF |
> + CDNS_I2C_IXR_RX_UNF | CDNS_I2C_IXR_TX_OVF)) {
> + id->slave_state = CDNS_I2C_SLAVE_STATE_IDLE;
> + i2c_slave_event(id->slave, I2C_SLAVE_STOP, NULL);
> + cdns_i2c_writereg(CDNS_I2C_CR_CLR_FIFO, CDNS_I2C_CR_OFFSET);
> + }
> +
> + return IRQ_HANDLED;
> +}
> +#endif
> +
> +/**
> + * cdns_i2c_master_isr - Interrupt handler for the I2C device in master role
> + * @ptr: Pointer to I2C device private data
> *
> * This function handles the data interrupt, transfer complete interrupt and
> - * the error interrupts of the I2C device.
> + * the error interrupts of the I2C device in master role.
> *
> * Return: IRQ_HANDLED always
> */
> -static irqreturn_t cdns_i2c_isr(int irq, void *ptr)
> +static irqreturn_t cdns_i2c_master_isr(void *ptr)
> {
> unsigned int isr_status, avail_bytes, updatetx;
> unsigned int bytes_to_send;
> @@ -352,6 +543,27 @@ static irqreturn_t cdns_i2c_isr(int irq, void *ptr)
> return status;
> }
>
> +/**
> + * cdns_i2c_isr - Interrupt handler for the I2C device
> + * @irq: irq number for the I2C device
> + * @ptr: void pointer to cdns_i2c structure
> + *
> + * This function passes the control to slave/master based on current role of
> + * i2c controller.
> + *
> + * Return: IRQ_HANDLED always
> + */
> +static irqreturn_t cdns_i2c_isr(int irq, void *ptr)
> +{
> +#if IS_ENABLED(CONFIG_I2C_SLAVE)
> + struct cdns_i2c *id = ptr;
> +
> + if (id->dev_mode == CDNS_I2C_MODE_SLAVE)
> + return cdns_i2c_slave_isr(ptr);
> +#endif
> + return cdns_i2c_master_isr(ptr);
> +}
> +
> /**
> * cdns_i2c_mrecv - Prepare and start a master receive operation
> * @id: pointer to the i2c device structure
> @@ -572,10 +784,28 @@ static int cdns_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
> u32 reg;
> struct cdns_i2c *id = adap->algo_data;
> bool hold_quirk;
> +#if IS_ENABLED(CONFIG_I2C_SLAVE)
> + bool change_role = false;
> +#endif
>
> ret = pm_runtime_get_sync(id->dev);
> if (ret < 0)
> return ret;
> +
> +#if IS_ENABLED(CONFIG_I2C_SLAVE)
> + /* Check i2c operating mode and switch if possible */
> + if (id->dev_mode == CDNS_I2C_MODE_SLAVE) {
> + if (id->slave_state != CDNS_I2C_SLAVE_STATE_IDLE)
> + return -EAGAIN;
> +
> + /* Set mode to master */
> + cdns_i2c_set_mode(CDNS_I2C_MODE_MASTER, id);
> +
> + /* Mark flag to change role once xfer is completed */
> + change_role = true;
> + }
> +#endif
> +
> /* Check if the bus is free */
> if (cdns_i2c_readreg(CDNS_I2C_SR_OFFSET) & CDNS_I2C_SR_BA) {
> ret = -EAGAIN;
> @@ -634,7 +864,15 @@ static int cdns_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
> }
>
> ret = num;
> +
> out:
> +
> +#if IS_ENABLED(CONFIG_I2C_SLAVE)
> + /* Switch i2c mode to slave */
> + if (change_role)
> + cdns_i2c_set_mode(CDNS_I2C_MODE_SLAVE, id);
> +#endif
> +
> pm_runtime_mark_last_busy(id->dev);
> pm_runtime_put_autosuspend(id->dev);
> return ret;
> @@ -648,14 +886,67 @@ static int cdns_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
> */
> static u32 cdns_i2c_func(struct i2c_adapter *adap)
> {
> - return I2C_FUNC_I2C | I2C_FUNC_10BIT_ADDR |
> - (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK) |
> - I2C_FUNC_SMBUS_BLOCK_DATA;
> + u32 func = I2C_FUNC_I2C | I2C_FUNC_10BIT_ADDR |
> + (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK) |
> + I2C_FUNC_SMBUS_BLOCK_DATA;
> +
> +#if IS_ENABLED(CONFIG_I2C_SLAVE)
> + func |= I2C_FUNC_SLAVE;
> +#endif
> +
> + return func;
> +}
> +
> +#if IS_ENABLED(CONFIG_I2C_SLAVE)
> +static int cdns_reg_slave(struct i2c_client *slave)
> +{
> + int ret;
> + struct cdns_i2c *id = container_of(slave->adapter, struct cdns_i2c,
> + adap);
> +
> + if (id->slave)
> + return -EBUSY;
> +
> + if (slave->flags & I2C_CLIENT_TEN)
> + return -EAFNOSUPPORT;
> +
> + ret = pm_runtime_get_sync(id->dev);
> + if (ret < 0)
> + return ret;
> +
> + /* Store slave information */
> + id->slave = slave;
> +
> + /* Enable I2C slave */
> + cdns_i2c_set_mode(CDNS_I2C_MODE_SLAVE, id);
> +
> + return 0;
> +}
> +
> +static int cdns_unreg_slave(struct i2c_client *slave)
> +{
> + struct cdns_i2c *id = container_of(slave->adapter, struct cdns_i2c,
> + adap);
> +
> + pm_runtime_put(id->dev);
> +
> + /* Remove slave information */
> + id->slave = NULL;
> +
> + /* Enable I2C master */
> + cdns_i2c_set_mode(CDNS_I2C_MODE_MASTER, id);
> +
> + return 0;
> }
> +#endif
>
> static const struct i2c_algorithm cdns_i2c_algo = {
> .master_xfer = cdns_i2c_master_xfer,
> .functionality = cdns_i2c_func,
> +#if IS_ENABLED(CONFIG_I2C_SLAVE)
> + .reg_slave = cdns_reg_slave,
> + .unreg_slave = cdns_unreg_slave,
> +#endif
> };
>
> /**
> @@ -750,6 +1041,8 @@ static int cdns_i2c_setclk(unsigned long clk_in, struct cdns_i2c *id)
> ctrl_reg |= ((div_a << CDNS_I2C_CR_DIVA_SHIFT) |
> (div_b << CDNS_I2C_CR_DIVB_SHIFT));
> cdns_i2c_writereg(ctrl_reg, CDNS_I2C_CR_OFFSET);
> + id->ctrl_reg_diva_divb = ctrl_reg & (CDNS_I2C_CR_DIVA_MASK |
> + CDNS_I2C_CR_DIVB_MASK);
>
> return 0;
> }
> @@ -943,8 +1236,12 @@ static int cdns_i2c_probe(struct platform_device *pdev)
> if (ret || (id->i2c_clk > CDNS_I2C_SPEED_MAX))
> id->i2c_clk = CDNS_I2C_SPEED_DEFAULT;
>
> - cdns_i2c_writereg(CDNS_I2C_CR_ACK_EN | CDNS_I2C_CR_NEA | CDNS_I2C_CR_MS,
> - CDNS_I2C_CR_OFFSET);
> +#if IS_ENABLED(CONFIG_I2C_SLAVE)
> + /* Set initial mode to master */
> + id->dev_mode = CDNS_I2C_MODE_MASTER;
> + id->slave_state = CDNS_I2C_SLAVE_STATE_IDLE;
> +#endif
> + cdns_i2c_writereg(CDNS_I2C_CR_MASTER_EN_MASK, CDNS_I2C_CR_OFFSET);
>
> ret = cdns_i2c_setclk(id->input_clk, id);
> if (ret) {
>

Shubhrajyoti: Please take a look at this one and discussion around.

Thanks,
Michal