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Date: Tue, 2 Dec 2014 15:35:49 +0530
From: Harini Katakam <harinik@...inx.com>
To: wsa@...-dreams.de, grant.likely@...aro.org, robh+dt@...nel.org,
pawel.moll@....com, mark.rutland@....com,
ijc+devicetree@...lion.org.uk, galak@...eaurora.org
Cc: michal.simek@...inx.com, soren.brinkmann@...inx.com,
linux-arm-kernel@...ts.infradead.org, linux-i2c@...r.kernel.org,
linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
harinik@...inx.com, vishnum@...inx.com
Subject: [PATCH 4/4] i2c: cadence: Defeature repeated start based on devicetree property
From: Vishnu Motghare <vishnum@...inx.com>
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 <vishnum@...inx.com>
Signed-off-by: Harini Katakam <harinik@...inx.com>
---
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
--
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