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

From: Biwen Li
Date: Fri Aug 09 2019 - 00:04:58 EST

>
> Hi,
>
> On Thu, Aug 08, 2019 at 11:53:43AM +0800, Biwen Li wrote:
> > The patch supports slave mode for imx I2C driver
> >
> > Signed-off-by: Biwen Li <biwen.li@xxxxxxx>
> > ---
> > 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 */
>
> Other drivers just do a "select I2C_SLAVE" in Kconfig to get rid of these #ifs. We
> should do the same.
Hi sascha, I don't know your meaning, could you let it clearer?
>
> > };
> >
> > 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__);
>
> Generally this driver has way too many dev_dbg spread around in hot pathes
> already. IMO adding more doesn't make the output more useful.
Ok, got it. I will delete it in v2.
>
> > +
> > + /* 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;
>
> unnecessary line break.
Ok, no problem. I will remove the line break in v2.
>
> > + 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;
>
> ditto.
Ok. I will remove the line break in v2.
>
> > + 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 */
>
> s/transimt/transmit/
You are right. I will correct it in v2.
>
> > + 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);
>
> value is unused, no need to assign a value to it.
Ok, I will correct this in v2.
>
> > + }
> > + } else {
> > + if (!(ctl & I2CR_MTX)) { /* Receive mode */
>
> Since you have an 'else' path please convert this to positive logic.
> This makes it easier to read.
Ok,got it, I will convert this to positive logic in v2.
>
> > + 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 */
>
> Same here.
Ok,got it, I will convert this to positive logic in v2.
>
> > + 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);
>
> Also value unused.
Ok,got it, I will correct this in v2.
>
> > + }
> > + }
> > + }
> > + 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;
>
> Better -EBUSY?
Yes, you are right, I will correct it in v2.
>
> Sascha
>
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