RE: [EXT] Re: i2c: imx: support slave mode for imx I2C driver

From: Biwen Li
Date: Thu Aug 08 2019 - 23:18:15 EST

> > The patch supports slave mode for imx I2C driver
> >
> > Signed-off-by: Biwen Li <biwen.li@xxxxxxx>
>
> Wow, this is much simpler than the other approach flying around:
>
> http://patchwork.ozlabs.org/patch/1124048/
>
> Can this one be master and slave on the same bus, too?
At the same time, the same bus is in master mode or slave mode.
>
> CCing the author of the other patch.
>
> > ---
> > drivers/i2c/busses/i2c-imx.c | 199
> > ++++++++++++++++++++++++++++++++---
> > 1 file changed, 185 insertions(+), 14 deletions(-)
> >
> > diff --git a/drivers/i2c/busses/i2c-imx.c
> > b/drivers/i2c/busses/i2c-imx.c index b1b8b938d7f4..f7583a9fa56f 100644
> > --- a/drivers/i2c/busses/i2c-imx.c
> > +++ b/drivers/i2c/busses/i2c-imx.c
> > @@ -202,6 +202,9 @@ struct imx_i2c_struct {
> > struct pinctrl_state *pinctrl_pins_gpio;
> >
> > struct imx_i2c_dma *dma;
> > +#if IS_ENABLED(CONFIG_I2C_SLAVE)
> > + struct i2c_client *slave;
> > +#endif /* CONFIG_I2C_SLAVE */
> > };
> >
> > static const struct imx_i2c_hwdata imx1_i2c_hwdata = { @@ -583,23
> > +586,40 @@ static void i2c_imx_stop(struct imx_i2c_struct *i2c_imx)
> > imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR); }
> >
> > -static irqreturn_t i2c_imx_isr(int irq, void *dev_id)
> > +/* Clear interrupt flag bit */
> > +static void i2c_imx_clr_if_bit(struct imx_i2c_struct *i2c_imx)
> > {
> > - struct imx_i2c_struct *i2c_imx = dev_id;
> > - unsigned int temp;
> > + unsigned int status;
> >
> > - temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2SR);
> > - if (temp & I2SR_IIF) {
> > - /* save status register */
> > - i2c_imx->i2csr = temp;
> > - temp &= ~I2SR_IIF;
> > - temp |= (i2c_imx->hwdata->i2sr_clr_opcode & I2SR_IIF);
> > - imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2SR);
> > - wake_up(&i2c_imx->queue);
> > - return IRQ_HANDLED;
> > - }
> > + status = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2SR);
> > + status &= ~I2SR_IIF;
> > + status |= (i2c_imx->hwdata->i2sr_clr_opcode & I2SR_IIF);
> > + imx_i2c_write_reg(status, i2c_imx, IMX_I2C_I2SR); }
> > +
> > +/* Clear arbitration lost bit */
> > +static void i2c_imx_clr_al_bit(struct imx_i2c_struct *i2c_imx) {
> > + unsigned int status;
> > +
> > + status = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2SR);
> > + status &= ~I2SR_IAL;
> > + imx_i2c_write_reg(status, i2c_imx, IMX_I2C_I2SR); }
> >
> > - return IRQ_NONE;
> > +static irqreturn_t i2c_imx_master_isr(struct imx_i2c_struct *i2c_imx)
> > +{
> > + unsigned int status;
> > +
> > + dev_dbg(&i2c_imx->adapter.dev, "<%s>: master interrupt\n",
> > +__func__);
> > +
> > + /* Save status register */
> > + status = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2SR);
> > + i2c_imx->i2csr = status | I2SR_IIF;
> > +
> > + wake_up(&i2c_imx->queue);
> > +
> > + return IRQ_HANDLED;
> > }
> >
> > static int i2c_imx_dma_write(struct imx_i2c_struct *i2c_imx, @@
> > -1043,11 +1063,162 @@ static u32 i2c_imx_func(struct i2c_adapter
> *adapter)
> > | I2C_FUNC_SMBUS_READ_BLOCK_DATA;
> > }
> >
> > +#if IS_ENABLED(CONFIG_I2C_SLAVE)
> > +static void i2c_imx_slave_init(struct imx_i2c_struct *i2c_imx) {
> > + unsigned int temp;
> > +
> > + dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__);
> > +
> > + /* Set slave addr. */
> > + imx_i2c_write_reg((i2c_imx->slave->addr << 1), i2c_imx,
> > +IMX_I2C_IADR);
> > +
> > + /* Disable i2c module */
> > + temp = i2c_imx->hwdata->i2cr_ien_opcode
> > + ^ I2CR_IEN;
> > + imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
> > +
> > + /* Reset status register */
> > + imx_i2c_write_reg(i2c_imx->hwdata->i2sr_clr_opcode, i2c_imx,
> > + IMX_I2C_I2SR);
> > +
> > + /* Enable module and enable interrupt from i2c module */
> > + temp = i2c_imx->hwdata->i2cr_ien_opcode
> > + | I2CR_IIEN;
> > + imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
> > +
> > + /* Wait controller to be stable */
> > + usleep_range(50, 150);
> > +}
> > +
> > +static irqreturn_t i2c_imx_slave_isr(struct imx_i2c_struct *i2c_imx)
> > +{
> > + unsigned int status, ctl;
> > + u8 value;
> > +
> > + if (!i2c_imx->slave) {
> > + dev_err(&i2c_imx->adapter.dev, "cannot deal with slave
> irq,i2c_imx->slave is null");
> > + return IRQ_NONE;
> > + }
> > +
> > + status = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2SR);
> > + ctl = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
> > + if (status & I2SR_IAL) { /* Arbitration lost */
> > + i2c_imx_clr_al_bit(i2c_imx);
> > + } else if (status & I2SR_IAAS) { /* Addressed as a slave */
> > + if (status & I2SR_SRW) { /* Master wants to read from us*/
> > + dev_dbg(&i2c_imx->adapter.dev, "read requested");
> > + i2c_slave_event(i2c_imx->slave, I2C_SLAVE_READ_REQUESTED,
> &value);
> > +
> > + /* Slave transimt */
> > + ctl |= I2CR_MTX;
> > + imx_i2c_write_reg(ctl, i2c_imx, IMX_I2C_I2CR);
> > +
> > + /* Send data */
> > + imx_i2c_write_reg(value, i2c_imx, IMX_I2C_I2DR);
> > + } else { /* Master wants to write to us */
> > + dev_dbg(&i2c_imx->adapter.dev, "write requested");
> > + i2c_slave_event(i2c_imx->slave,
> I2C_SLAVE_WRITE_REQUESTED, &value);
> > +
> > + /* Slave receive */
> > + ctl &= ~I2CR_MTX;
> > + imx_i2c_write_reg(ctl, i2c_imx, IMX_I2C_I2CR);
> > + /* Dummy read */
> > + value = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2DR);
> > + }
> > + } else {
> > + if (!(ctl & I2CR_MTX)) { /* Receive mode */
> > + if (status & I2SR_IBB) { /* No STOP signal detected */
> > + ctl &= ~I2CR_MTX;
> > + imx_i2c_write_reg(ctl, i2c_imx, IMX_I2C_I2CR);
> > +
> > + value = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2DR);
> > + i2c_slave_event(i2c_imx->slave,
> I2C_SLAVE_WRITE_RECEIVED, &value);
> > + } else { /* STOP signal is detected */
> > + dev_dbg(&i2c_imx->adapter.dev,
> > + "STOP signal detected");
> > + i2c_slave_event(i2c_imx->slave, I2C_SLAVE_STOP, &value);
> > + }
> > + } else { /* Transmit mode */
> > + if (!(status & I2SR_RXAK)) { /* Received ACK */
> > + ctl |= I2CR_MTX;
> > + imx_i2c_write_reg(ctl, i2c_imx, IMX_I2C_I2CR);
> > +
> > + i2c_slave_event(i2c_imx->slave,
> I2C_SLAVE_READ_PROCESSED, &value);
> > +
> > + imx_i2c_write_reg(value, i2c_imx, IMX_I2C_I2DR);
> > + } else { /* Received NAK */
> > + ctl &= ~I2CR_MTX;
> > + imx_i2c_write_reg(ctl, i2c_imx, IMX_I2C_I2CR);
> > + value = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2DR);
> > + }
> > + }
> > + }
> > + return IRQ_HANDLED;
> > +}
> > +
> > +static int i2c_imx_reg_slave(struct i2c_client *client) {
> > + struct imx_i2c_struct *i2c_imx = i2c_get_adapdata(client->adapter);
> > +
> > + if (i2c_imx->slave)
> > + return -EINVAL;
> > +
> > + dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__);
> > + i2c_imx->slave = client;
> > +
> > + i2c_imx_slave_init(i2c_imx);
> > +
> > + return 0;
> > +}
> > +
> > +static int i2c_imx_unreg_slave(struct i2c_client *client) {
> > + struct imx_i2c_struct *i2c_imx = i2c_get_adapdata(client->adapter);
> > +
> > + if (!i2c_imx->slave)
> > + return -EINVAL;
> > +
> > + i2c_imx->slave = NULL;
> > +
> > + return 0;
> > +}
> > +#endif /* CONFIG_I2C_SLAVE */
> > +
> > static const struct i2c_algorithm i2c_imx_algo = {
> > .master_xfer = i2c_imx_xfer,
> > .functionality = i2c_imx_func,
> > +#if IS_ENABLED(CONFIG_I2C_SLAVE)
> > + .reg_slave = i2c_imx_reg_slave,
> > + .unreg_slave = i2c_imx_unreg_slave,
> > +#endif /* CONFIG_I2C_SLAVE */
> > };
> >
> > +static irqreturn_t i2c_imx_isr(int irq, void *dev_id) {
> > + struct imx_i2c_struct *i2c_imx = dev_id;
> > + unsigned int status, ctl;
> > + irqreturn_t irq_status = IRQ_NONE;
> > +
> > + status = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2SR);
> > + ctl = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
> > +
> > + if (status & I2SR_IIF) {
> > + i2c_imx_clr_if_bit(i2c_imx);
> > +#if IS_ENABLED(CONFIG_I2C_SLAVE)
> > + if (ctl & I2CR_MSTA)
> > + irq_status = i2c_imx_master_isr(i2c_imx);
> > + else
> > + irq_status = i2c_imx_slave_isr(i2c_imx); #else
> > + irq_status = i2c_imx_master_isr(i2c_imx);
> > +
> > +#endif /* CONFIG_I2C_SLAVE */
> > + }
> > +
> > + return irq_status;
> > +}
> > +
> > static int i2c_imx_probe(struct platform_device *pdev) {
> > const struct of_device_id *of_id = of_match_device(i2c_imx_dt_ids,
> > --
> > 2.17.1
> >