[PATCH v4 1/2] i2c: lpi2c: use readl_poll_timeout() for register polling

Francesco Dolcini
2025-05-23T08:45:15Z

From: Emanuele Ghidoli <emanuele.ghidoli@toradex.com>

Replace polling loops with the readl_poll_timeout() helper macro.

Signed-off-by: Emanuele Ghidoli <emanuele.ghidoli@toradex.com>
Signed-off-by: Francesco Dolcini <francesco.dolcini@toradex.com>
Reviewed-by: Carlos Song <carlos.song@nxp.com>
---
v3 -> v4
- Split the patch into two parts: one for the readl_poll_timeout() and one for the atomic implementation.
- Change the readl_poll_timeout() delay to 0 us to do not change the behavior of the driver.
- Use err variable consistently.

v2 -> v3
- Closes: https://lore.kernel.org/oe-kbuild-all/202505130735.zh3WuTNu-lkp@intel.com/. Using the return value of
lpi2c_imx_read_msr_poll_timeout() to check for errors.

v1 -> v2
- Rename READL_POLL_TIMEOUT to lpi2c_imx_read_msr_poll_timeout
- Remove addr and timeout_us parameters from lpi2c_imx_read_msr_poll_timeout since they are used always with the same value
- add r-b tag from Carlos Song
---
drivers/i2c/busses/i2c-imx-lpi2c.c | 94 ++++++++++++++----------------
1 file changed, 45 insertions(+), 49 deletions(-)

diff --git a/drivers/i2c/busses/i2c-imx-lpi2c.c b/drivers/i2c/busses/i2c-imx-lpi2c.c
index 342d47e67586..91b0f4c2b924 100644
--- a/drivers/i2c/busses/i2c-imx-lpi2c.c
+++ b/drivers/i2c/busses/i2c-imx-lpi2c.c
@@ -16,6 +16,7 @@
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/io.h>
+#include <linux/iopoll.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
@@ -187,6 +188,10 @@ struct lpi2c_imx_struct {
struct i2c_client *target;
};

+#define lpi2c_imx_read_msr_poll_timeout(val, cond) \
+ readl_poll_timeout(lpi2c_imx->base + LPI2C_MSR, val, cond, \
+ 0, 500000)
+
static void lpi2c_imx_intctrl(struct lpi2c_imx_struct *lpi2c_imx,
unsigned int enable)
{
@@ -195,33 +200,34 @@ static void lpi2c_imx_intctrl(struct lpi2c_imx_struct *lpi2c_imx,

static int lpi2c_imx_bus_busy(struct lpi2c_imx_struct *lpi2c_imx)
{
- unsigned long orig_jiffies = jiffies;
+ int err;
unsigned int temp;

- while (1) {
- temp = readl(lpi2c_imx->base + LPI2C_MSR);
-
- /* check for arbitration lost, clear if set */
- if (temp & MSR_ALF) {
- writel(temp, lpi2c_imx->base + LPI2C_MSR);
- return -EAGAIN;
- }
+ err = lpi2c_imx_read_msr_poll_timeout(temp,
+ temp & (MSR_ALF | MSR_BBF | MSR_MBF));

- if (temp & (MSR_BBF | MSR_MBF))
- break;
+ /* check for arbitration lost, clear if set */
+ if (temp & MSR_ALF) {
+ writel(temp, lpi2c_imx->base + LPI2C_MSR);
+ return -EAGAIN;
+ }

- if (time_after(jiffies, orig_jiffies + msecs_to_jiffies(500))) {
- dev_dbg(&lpi2c_imx->adapter.dev, "bus not work\n");
- if (lpi2c_imx->adapter.bus_recovery_info)
- i2c_recover_bus(&lpi2c_imx->adapter);
- return -ETIMEDOUT;
- }
- schedule();
+ /* check for bus not busy */
+ if (err) {
+ dev_dbg(&lpi2c_imx->adapter.dev, "bus not work\n");
+ if (lpi2c_imx->adapter.bus_recovery_info)
+ i2c_recover_bus(&lpi2c_imx->adapter);
+ return -ETIMEDOUT;
}

return 0;
}

+static u32 lpi2c_imx_txfifo_cnt(struct lpi2c_imx_struct *lpi2c_imx)
+{
+ return readl(lpi2c_imx->base + LPI2C_MFSR) & 0xff;
+}
+
static void lpi2c_imx_set_mode(struct lpi2c_imx_struct *lpi2c_imx)
{
unsigned int bitrate = lpi2c_imx->bitrate;
@@ -259,25 +265,18 @@ static int lpi2c_imx_start(struct lpi2c_imx_struct *lpi2c_imx,

static void lpi2c_imx_stop(struct lpi2c_imx_struct *lpi2c_imx)
{
- unsigned long orig_jiffies = jiffies;
unsigned int temp;
+ int err;

writel(GEN_STOP << 8, lpi2c_imx->base + LPI2C_MTDR);

- do {
- temp = readl(lpi2c_imx->base + LPI2C_MSR);
- if (temp & MSR_SDF)
- break;
+ err = lpi2c_imx_read_msr_poll_timeout(temp, temp & MSR_SDF);

- if (time_after(jiffies, orig_jiffies + msecs_to_jiffies(500))) {
- dev_dbg(&lpi2c_imx->adapter.dev, "stop timeout\n");
- if (lpi2c_imx->adapter.bus_recovery_info)
- i2c_recover_bus(&lpi2c_imx->adapter);
- break;
- }
- schedule();
-
- } while (1);
+ if (err) {
+ dev_dbg(&lpi2c_imx->adapter.dev, "stop timeout\n");
+ if (lpi2c_imx->adapter.bus_recovery_info)
+ i2c_recover_bus(&lpi2c_imx->adapter);
+ }
}

/* CLKLO = I2C_CLK_RATIO * CLKHI, SETHOLD = CLKHI, DATAVD = CLKHI/2 */
@@ -393,26 +392,23 @@ static int lpi2c_imx_pio_msg_complete(struct lpi2c_imx_struct *lpi2c_imx)

static int lpi2c_imx_txfifo_empty(struct lpi2c_imx_struct *lpi2c_imx)
{
- unsigned long orig_jiffies = jiffies;
- u32 txcnt;
-
- do {
- txcnt = readl(lpi2c_imx->base + LPI2C_MFSR) & 0xff;
+ unsigned int temp;
+ int err;

- if (readl(lpi2c_imx->base + LPI2C_MSR) & MSR_NDF) {
- dev_dbg(&lpi2c_imx->adapter.dev, "NDF detected\n");
- return -EIO;
- }
+ err = lpi2c_imx_read_msr_poll_timeout(temp,
+ (temp & MSR_NDF) || !lpi2c_imx_txfifo_cnt(lpi2c_imx));

- if (time_after(jiffies, orig_jiffies + msecs_to_jiffies(500))) {
- dev_dbg(&lpi2c_imx->adapter.dev, "txfifo empty timeout\n");
- if (lpi2c_imx->adapter.bus_recovery_info)
- i2c_recover_bus(&lpi2c_imx->adapter);
- return -ETIMEDOUT;
- }
- schedule();
+ if (temp & MSR_NDF) {
+ dev_dbg(&lpi2c_imx->adapter.dev, "NDF detected\n");
+ return -EIO;
+ }

- } while (txcnt);
+ if (err) {
+ dev_dbg(&lpi2c_imx->adapter.dev, "txfifo empty timeout\n");
+ if (lpi2c_imx->adapter.bus_recovery_info)
+ i2c_recover_bus(&lpi2c_imx->adapter);
+ return -ETIMEDOUT;
+ }

return 0;
}
--
2.39.5