Hello Greg,
On Sun, 21 Apr 2024, Marc Dietrich wrote:
The i2c controller needs to read back the data written to its registers.
This way we can avoid the long delay in the interrupt handler.
Signed-off-by: Marc Dietrich <marvin24@xxxxxx>
---
drivers/staging/nvec/nvec.c | 41 ++++++++++++++++++++++---------------
1 file changed, 24 insertions(+), 17 deletions(-)
I think I answered all remaining comments. Are there any other
objections?
Best wishes,
Marc
diff --git a/drivers/staging/nvec/nvec.c b/drivers/staging/nvec/nvec.c
index 45df190c2f94..214839f51048 100644
--- a/drivers/staging/nvec/nvec.c
+++ b/drivers/staging/nvec/nvec.c
@@ -570,6 +570,22 @@ static void nvec_tx_set(struct nvec_chip *nvec)
(uint)nvec->tx->size, nvec->tx->data[1]);
}
+/**
+ * i2c_writel - safely write to an I2C client controller register
+ * @val: value to be written
+ * @reg: register to write to
+ *
+ * A write to an I2C controller register needs to be read back to make sure
+ * that the value has arrived.
+ */
+static void i2c_writel(u32 val, void *reg)
+{
+ writel_relaxed(val, reg);
+
+ /* read back register to make sure that register writes completed */
+ readl_relaxed(reg);
+}
+
/**
* nvec_interrupt - Interrupt handler
* @irq: The IRQ
@@ -604,7 +620,7 @@ static irqreturn_t nvec_interrupt(int irq, void *dev)
if ((status & RNW) == 0) {
received = readl(nvec->base + I2C_SL_RCVD);
if (status & RCVD)
- writel(0, nvec->base + I2C_SL_RCVD);
+ i2c_writel(0, nvec->base + I2C_SL_RCVD);
}
if (status == (I2C_SL_IRQ | RCVD))
@@ -696,7 +712,7 @@ static irqreturn_t nvec_interrupt(int irq, void *dev)
/* Send data if requested, but not on end of transmission */
if ((status & (RNW | END_TRANS)) == RNW)
- writel(to_send, nvec->base + I2C_SL_RCVD);
+ i2c_writel(to_send, nvec->base + I2C_SL_RCVD);
/* If we have send the first byte */
if (status == (I2C_SL_IRQ | RNW | RCVD))
@@ -713,15 +729,6 @@ static irqreturn_t nvec_interrupt(int irq, void *dev)
status & RCVD ? " RCVD" : "",
status & RNW ? " RNW" : "");
- /*
- * TODO: replace the udelay with a read back after each writel above
- * in order to work around a hardware issue, see i2c-tegra.c
- *
- * Unfortunately, this change causes an initialisation issue with the
- * touchpad, which needs to be fixed first.
- */
- udelay(100);
-
return IRQ_HANDLED;
}
@@ -737,15 +744,15 @@ static void tegra_init_i2c_slave(struct nvec_chip *nvec)
val = I2C_CNFG_NEW_MASTER_SFM | I2C_CNFG_PACKET_MODE_EN |
(0x2 << I2C_CNFG_DEBOUNCE_CNT_SHIFT);
- writel(val, nvec->base + I2C_CNFG);
+ i2c_writel(val, nvec->base + I2C_CNFG);
clk_set_rate(nvec->i2c_clk, 8 * 80000);
- writel(I2C_SL_NEWSL, nvec->base + I2C_SL_CNFG);
- writel(0x1E, nvec->base + I2C_SL_DELAY_COUNT);
+ i2c_writel(I2C_SL_NEWSL, nvec->base + I2C_SL_CNFG);
+ i2c_writel(0x1E, nvec->base + I2C_SL_DELAY_COUNT);
- writel(nvec->i2c_addr >> 1, nvec->base + I2C_SL_ADDR1);
- writel(0, nvec->base + I2C_SL_ADDR2);
+ i2c_writel(nvec->i2c_addr >> 1, nvec->base + I2C_SL_ADDR1);
+ i2c_writel(0, nvec->base + I2C_SL_ADDR2);
enable_irq(nvec->irq);
}
@@ -754,7 +761,7 @@ static void tegra_init_i2c_slave(struct nvec_chip *nvec)
static void nvec_disable_i2c_slave(struct nvec_chip *nvec)
{
disable_irq(nvec->irq);
- writel(I2C_SL_NEWSL | I2C_SL_NACK, nvec->base + I2C_SL_CNFG);
+ i2c_writel(I2C_SL_NEWSL | I2C_SL_NACK, nvec->base + I2C_SL_CNFG);
clk_disable_unprepare(nvec->i2c_clk);
}
#endif
--
2.43.0
