[PATCH v2 2/4] i2c: omap24xx_i2c: Use new function __omap24_i2c_xfer_msg()
Aniket Limaye
a-limaye at ti.com
Mon Mar 10 11:36:45 CET 2025
Remove __omap24_i2c_read/write() usage from omap_i2c_xfer() in favour of
the more flexible __omap24_i2c_xfer_msg().
Consequently, these are also no longer needed when DM_I2C is enabled.
New function __omap24_i2c_xfer_msg() will take care of individual read
OR write transfers with a target device. It goes through below sequence:
- Program the provided Target Chip address (OMAP_I2C_SA_REG)
- Program the provided Data len (OMAP_I2C_CNT_REG)
- Program the provided Control register flags (OMAP_I2C_CON_REG)
- Read from or Write to the provided Data buffer (OMAP_I2C_DATA_REG)
For a detailed programming guide, refer to the TRM[0] (12.1.3.4 I2C
Programming Guide).
This patch by itself should be a transparent change. However this is
needed for implementing a proper Repeated Start (Sr) functionality for
i2c_msgs.
Previous implementation for omap_i2c_xfer called __omap24_i2c_read/write
functions, with hardcoded addr=0 and alen=0 for each i2c_msg. Each of
these calls would program the registers always with a Stop bit set, not
allowing for a repeated start between i2c_msgs in the same xfer().
[0]: https://www.ti.com/lit/zip/spruj28 (TRM)
Signed-off-by: Aniket Limaye <a-limaye at ti.com>
---
v2:
- Use proper error codes in __omap24_i2c_xfer_msg()
- Use proper error prints to indicate omap24xx i2c driver
- Link to v1: https://lore.kernel.org/u-boot/20250304220546.866602-2-a-limaye@ti.com/
---
drivers/i2c/omap24xx_i2c.c | 143 +++++++++++++++++++++++++++++++------
1 file changed, 123 insertions(+), 20 deletions(-)
diff --git a/drivers/i2c/omap24xx_i2c.c b/drivers/i2c/omap24xx_i2c.c
index 1fd5f5cc224..7c5d786e8e9 100644
--- a/drivers/i2c/omap24xx_i2c.c
+++ b/drivers/i2c/omap24xx_i2c.c
@@ -535,6 +535,107 @@ pr_exit:
return res;
}
+static int __omap24_i2c_xfer_msg(void __iomem *i2c_base, int ip_rev, int waitdelay,
+ uchar chip, uchar *buffer, int len, u16 i2c_con_reg)
+{
+ int i;
+ u16 status;
+ int i2c_error = 0;
+ int timeout = I2C_TIMEOUT;
+
+ if (len < 0) {
+ printf("%s: data len < 0\n", __func__);
+ return -EINVAL;
+ }
+
+ if (!buffer) {
+ printf("%s: NULL pointer passed\n", __func__);
+ return -EINVAL;
+ }
+
+ if (!(i2c_con_reg & I2C_CON_EN)) {
+ printf("%s: I2C_CON_EN not set\n", __func__);
+ return -EINVAL;
+ }
+
+ /* Set slave address */
+ omap_i2c_write_reg(i2c_base, ip_rev, chip, OMAP_I2C_SA_REG);
+ /* Read/Write len bytes data */
+ omap_i2c_write_reg(i2c_base, ip_rev, len, OMAP_I2C_CNT_REG);
+ /* Configure the I2C_CON register */
+ omap_i2c_write_reg(i2c_base, ip_rev, i2c_con_reg, OMAP_I2C_CON_REG);
+
+ /* read/write data bytewise */
+ for (i = 0; i < len; i++) {
+ status = wait_for_event(i2c_base, ip_rev, waitdelay);
+ /* Ignore I2C_STAT_RRDY in transmitter mode */
+ if (i2c_con_reg & I2C_CON_TRX)
+ status &= ~I2C_STAT_RRDY;
+ else
+ status &= ~I2C_STAT_XRDY;
+
+ /* Try to identify bus that is not padconf'd for I2C */
+ if (status == I2C_STAT_XRDY) {
+ i2c_error = -EREMOTEIO;
+ printf("%s: pads on bus probably not configured (status=0x%x)\n",
+ __func__, status);
+ goto xfer_exit;
+ }
+ if (status == 0 || (status & I2C_STAT_NACK)) {
+ i2c_error = -EREMOTEIO;
+ printf("%s: error waiting for ACK (status=0x%x)\n",
+ __func__, status);
+ goto xfer_exit;
+ }
+ if (status & I2C_STAT_XRDY) {
+ /* Transmit data */
+ omap_i2c_write_reg(i2c_base, ip_rev,
+ buffer[i], OMAP_I2C_DATA_REG);
+ omap_i2c_write_reg(i2c_base, ip_rev,
+ I2C_STAT_XRDY, OMAP_I2C_STAT_REG);
+ }
+ if (status & I2C_STAT_RRDY) {
+ /* Receive data */
+ *buffer++ = omap_i2c_read_reg(i2c_base, ip_rev,
+ OMAP_I2C_DATA_REG);
+ omap_i2c_write_reg(i2c_base, ip_rev,
+ I2C_STAT_RRDY, OMAP_I2C_STAT_REG);
+ }
+ }
+
+ /*
+ * poll ARDY bit for making sure that last byte really has been
+ * transferred on the bus.
+ */
+ do {
+ status = wait_for_event(i2c_base, ip_rev, waitdelay);
+ } while (!(status & I2C_STAT_ARDY) && timeout--);
+ if (timeout <= 0) {
+ printf("%s: timed out on last byte!\n", __func__);
+ i2c_error = -EREMOTEIO;
+ goto xfer_exit;
+ } else {
+ omap_i2c_write_reg(i2c_base, ip_rev, I2C_STAT_ARDY, OMAP_I2C_STAT_REG);
+ }
+
+ /* If Stop bit set, flush FIFO. */
+ if (i2c_con_reg & I2C_CON_STP)
+ goto xfer_exit;
+
+ return 0;
+
+xfer_exit:
+ flush_fifo(i2c_base, ip_rev);
+ omap_i2c_write_reg(i2c_base, ip_rev, 0xFFFF, OMAP_I2C_STAT_REG);
+ return i2c_error;
+}
+
+#if !CONFIG_IS_ENABLED(DM_I2C)
+/*
+ * The legacy I2C functions. These need to get removed once
+ * all users of this driver are converted to DM.
+ */
+
/*
* i2c_read: Function now uses a single I2C read transaction with bulk transfer
* of the requested number of bytes (note that the 'i2c md' command
@@ -828,11 +929,6 @@ wr_exit:
return i2c_error;
}
-#if !CONFIG_IS_ENABLED(DM_I2C)
-/*
- * The legacy I2C functions. These need to get removed once
- * all users of this driver are converted to DM.
- */
static void __iomem *omap24_get_base(struct i2c_adapter *adap)
{
switch (adap->hwadapnr) {
@@ -967,24 +1063,31 @@ static int omap_i2c_xfer(struct udevice *bus, struct i2c_msg *msg, int nmsgs)
{
struct omap_i2c *priv = dev_get_priv(bus);
int ret;
+ u16 i2c_con_reg = 0;
- debug("i2c_xfer: %d messages\n", nmsgs);
+ debug("%s: %d messages\n", __func__, nmsgs);
for (; nmsgs > 0; nmsgs--, msg++) {
- debug("i2c_xfer: chip=0x%x, len=0x%x\n", msg->addr, msg->len);
- if (msg->flags & I2C_M_RD) {
- ret = __omap24_i2c_read(priv->regs, priv->ip_rev,
- priv->waitdelay,
- msg->addr, 0, 0, msg->buf,
- msg->len);
- } else {
- ret = __omap24_i2c_write(priv->regs, priv->ip_rev,
- priv->waitdelay,
- msg->addr, 0, 0, msg->buf,
- msg->len);
- }
- if (ret) {
- debug("i2c_write: error sending\n");
+ /* Wait until bus not busy */
+ if (wait_for_bb(priv->regs, priv->ip_rev, priv->waitdelay))
return -EREMOTEIO;
+
+ /* Set Controller mode with Start and Stop bit */
+ i2c_con_reg = I2C_CON_EN | I2C_CON_MST | I2C_CON_STT | I2C_CON_STP;
+ /* Set Transmitter/Receiver mode if it is a write/read msg */
+ if (msg->flags & I2C_M_RD)
+ i2c_con_reg &= ~I2C_CON_TRX;
+ else
+ i2c_con_reg |= I2C_CON_TRX;
+
+ debug("%s: chip=0x%x, len=0x%x, i2c_con_reg=0x%x\n",
+ __func__, msg->addr, msg->len, i2c_con_reg);
+
+ ret = __omap24_i2c_xfer_msg(priv->regs, priv->ip_rev, priv->waitdelay,
+ msg->addr, msg->buf, msg->len,
+ i2c_con_reg);
+ if (ret) {
+ printf("%s: errored out at msg %d: %d\n", __func__, i, ret);
+ return ret;
}
}
--
2.48.1
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