From: Vishnu Motghare <[email protected]> This patch defeatures repeated start in the driver if "defeature-repeated-start" property is present in the devicetree.
This defeature is proposed due to a few bugs in the controller - completion indication is not given to the driver at the end of a read/receive transfer with HOLD bit set. - Invalid read transaction are generated on the bus when HW timeout condition occurs with HOLD bit set. Signed-off-by: Vishnu Motghare <[email protected]> Signed-off-by: Harini Katakam <[email protected]> --- drivers/i2c/busses/i2c-cadence.c | 44 +++++++++++++++++++++++++++----------- 1 file changed, 31 insertions(+), 13 deletions(-) diff --git a/drivers/i2c/busses/i2c-cadence.c b/drivers/i2c/busses/i2c-cadence.c index 8065205..89335f7 100644 --- a/drivers/i2c/busses/i2c-cadence.c +++ b/drivers/i2c/busses/i2c-cadence.c @@ -135,6 +135,7 @@ * @bus_hold_flag: Flag used in repeated start for clearing HOLD bit * @clk: Pointer to struct clk * @clk_rate_change_nb: Notifier block for clock rate changes + * @defeature_repeated_start: Flag to de feature repeated start */ struct cdns_i2c { void __iomem *membase; @@ -154,6 +155,7 @@ struct cdns_i2c { unsigned int bus_hold_flag; struct clk *clk; struct notifier_block clk_rate_change_nb; + unsigned int defeature_repeated_start; }; #define to_cdns_i2c(_nb) container_of(_nb, struct cdns_i2c, \ @@ -246,7 +248,7 @@ static irqreturn_t cdns_i2c_isr(int irq, void *ptr) } if ((isr_status & CDNS_I2C_IXR_COMP) && !id->recv_count) { - if (!id->bus_hold_flag) + if (id->defeature_repeated_start || !id->bus_hold_flag) cdns_i2c_clear_bus_hold(id); done_flag = 1; } @@ -283,7 +285,8 @@ static irqreturn_t cdns_i2c_isr(int irq, void *ptr) */ done_flag = 1; } - if (!id->send_count && !id->bus_hold_flag) + if ((id->defeature_repeated_start && !id->send_count) || + (!id->send_count && !id->bus_hold_flag)) cdns_i2c_clear_bus_hold(id); status = IRQ_HANDLED; @@ -347,10 +350,15 @@ static void cdns_i2c_mrecv(struct cdns_i2c *id) } else cdns_i2c_writereg(id->recv_count, CDNS_I2C_XFER_SIZE_OFFSET); /* Clear the bus hold flag if bytes to receive is less than FIFO size */ - if (!id->bus_hold_flag && - ((id->p_msg->flags & I2C_M_RECV_LEN) != I2C_M_RECV_LEN) && - (id->recv_count <= CDNS_I2C_FIFO_DEPTH)) - cdns_i2c_clear_bus_hold(id); + if (id->defeature_repeated_start && + (((id->p_msg->flags & I2C_M_RECV_LEN) != I2C_M_RECV_LEN) && + (id->recv_count <= CDNS_I2C_FIFO_DEPTH))) + cdns_i2c_clear_bus_hold(id); + else if (!id->bus_hold_flag && + ((id->p_msg->flags & I2C_M_RECV_LEN) != I2C_M_RECV_LEN) && + (id->recv_count <= CDNS_I2C_FIFO_DEPTH)) + cdns_i2c_clear_bus_hold(id); + /* Set the slave address in address register - triggers operation */ cdns_i2c_writereg(id->p_msg->addr & CDNS_I2C_ADDR_MASK, CDNS_I2C_ADDR_OFFSET); @@ -411,8 +419,10 @@ static void cdns_i2c_msend(struct cdns_i2c *id) * Clear the bus hold flag if there is no more data * and if it is the last message. */ - if (!id->bus_hold_flag && !id->send_count) + if ((id->defeature_repeated_start && !id->send_count) || + (!id->send_count && !id->bus_hold_flag)) cdns_i2c_clear_bus_hold(id); + /* Set the slave address in address register - triggers operation. */ cdns_i2c_writereg(id->p_msg->addr & CDNS_I2C_ADDR_MASK, CDNS_I2C_ADDR_OFFSET); @@ -520,19 +530,25 @@ static int cdns_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, /* * Set the flag to one when multiple messages are to be * processed with a repeated start. + * De feature repeated start when defeature_repeated_start flag is set */ - if (num > 1) { - id->bus_hold_flag = 1; - reg = cdns_i2c_readreg(CDNS_I2C_CR_OFFSET); - reg |= CDNS_I2C_CR_HOLD; - cdns_i2c_writereg(reg, CDNS_I2C_CR_OFFSET); + if (!id->defeature_repeated_start && num > 1) { + for (count = 0; count < num-1; count++) { + if (msgs[count].flags & I2C_M_RD) + return -EINVAL; + } + id->bus_hold_flag = 1; + reg = cdns_i2c_readreg(CDNS_I2C_CR_OFFSET); + reg |= CDNS_I2C_CR_HOLD; + cdns_i2c_writereg(reg, CDNS_I2C_CR_OFFSET); } else { id->bus_hold_flag = 0; } /* Process the msg one by one */ for (count = 0; count < num; count++, msgs++) { - if (count == (num - 1)) + if (!id->defeature_repeated_start && + (count == (num - 1))) id->bus_hold_flag = 0; ret = cdns_i2c_process_msg(id, msgs, adap); @@ -840,6 +856,8 @@ static int cdns_i2c_probe(struct platform_device *pdev) cdns_i2c_writereg(CDNS_I2C_CR_ACK_EN | CDNS_I2C_CR_NEA | CDNS_I2C_CR_MS, CDNS_I2C_CR_OFFSET); + of_property_read_u32(pdev->dev.of_node, "defeature-repeated-start", + &id->defeature_repeated_start); ret = cdns_i2c_setclk(id->input_clk, id); if (ret) { dev_err(&pdev->dev, "invalid SCL clock: %u Hz\n", id->i2c_clk); -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
