Rework the read and write code paths in the driver to support operation
in IRQ disabled contexts. The patch is currently tested only on a
phyCORE-i.MX6 Solo board.
The driver supports normal operation, DMA transfers and now the polling
mode or also called sleep-free or IRQ-less operation. It makes the code
not simpler or easier to read, but IRQ less I2C transfers are needed on
some hardware configurations, e.g. to trigger a reboot in an external
PMIC chip.
TODOs:
- checkpatch complains that in_atomic() should not be used in driver
code.
Signed-off-by: Stefan Lengfeld <contact@xxxxxxxxxxxxxxx>
---
drivers/i2c/busses/i2c-imx.c | 113 +++++++++++++++++++++++++++++++------------
1 file changed, 81 insertions(+), 32 deletions(-)
diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index 498c5e891649..8a17c8c454c7 100644
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -404,7 +404,7 @@ static void i2c_imx_dma_free(struct imx_i2c_struct *i2c_imx)
dma->chan_using = NULL;
}
-static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx, int for_busy)
+static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx, int for_busy, bool polling)
{
unsigned long orig_jiffies = jiffies;
unsigned int temp;
@@ -430,15 +430,39 @@ static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx, int for_busy)
"<%s> I2C bus is busy\n", __func__);
return -ETIMEDOUT;
}
- schedule();
+ if (!polling)
+ schedule();
+ else
+ udelay(100);
}
return 0;
}
-static int i2c_imx_trx_complete(struct imx_i2c_struct *i2c_imx)
+static int i2c_imx_trx_complete(struct imx_i2c_struct *i2c_imx, bool polling)
{
- wait_event_timeout(i2c_imx->queue, i2c_imx->i2csr & I2SR_IIF, HZ / 10);
+ if (!polling) {
+ wait_event_timeout(i2c_imx->queue, i2c_imx->i2csr & I2SR_IIF, HZ / 10);
+ } else {
+ int counter = 0;
+
+ while (1) {
+ unsigned int reg;
+
+ reg = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2SR);
+ i2c_imx->i2csr = reg;
+ if (reg & I2SR_IIF)
+ break;
+
+ if (counter > 1000) {
+ dev_err(&i2c_imx->adapter.dev, "<%s> TXR timeout\n", __func__);
+ return -EIO;
+ }
+ udelay(100);
+ counter++;
+ }
+ imx_i2c_write_reg(0, i2c_imx, IMX_I2C_I2SR);
+ }
if (unlikely(!(i2c_imx->i2csr & I2SR_IIF))) {
dev_dbg(&i2c_imx->adapter.dev, "<%s> Timeout\n", __func__);
@@ -516,7 +540,7 @@ static int i2c_imx_clk_notifier_call(struct notifier_block *nb,
return NOTIFY_OK;
}
-static int i2c_imx_start(struct imx_i2c_struct *i2c_imx)
+static int i2c_imx_start(struct imx_i2c_struct *i2c_imx, bool polling)
{
unsigned int temp = 0;
int result;
@@ -529,24 +553,33 @@ static int i2c_imx_start(struct imx_i2c_struct *i2c_imx)
imx_i2c_write_reg(i2c_imx->hwdata->i2cr_ien_opcode, i2c_imx, IMX_I2C_I2CR);
/* Wait controller to be stable */
- usleep_range(50, 150);
+ if (!polling)
+ usleep_range(50, 150);
+ else
+ udelay(50);
/* Start I2C transaction */
temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
temp |= I2CR_MSTA;
imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
- result = i2c_imx_bus_busy(i2c_imx, 1);
+ result = i2c_imx_bus_busy(i2c_imx, 1, polling);
if (result)
return result;
i2c_imx->stopped = 0;
- temp |= I2CR_IIEN | I2CR_MTX | I2CR_TXAK;
+ if (!polling) {
+ temp |= I2CR_IIEN | I2CR_MTX | I2CR_TXAK;
+ } else {
+ temp |= I2CR_MTX | I2CR_TXAK;
+ temp &= ~I2CR_IIEN; /* Disable interrupt */
+ }
+
temp &= ~I2CR_DMAEN;
imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
return result;
}
-static void i2c_imx_stop(struct imx_i2c_struct *i2c_imx)
+static void i2c_imx_stop(struct imx_i2c_struct *i2c_imx, bool polling)
{
unsigned int temp = 0;
@@ -568,7 +601,7 @@ static void i2c_imx_stop(struct imx_i2c_struct *i2c_imx)
}
if (!i2c_imx->stopped) {
- i2c_imx_bus_busy(i2c_imx, 0);
+ i2c_imx_bus_busy(i2c_imx, 0, polling);
i2c_imx->stopped = 1;
}
@@ -651,7 +684,7 @@ static int i2c_imx_dma_write(struct imx_i2c_struct *i2c_imx,
/* The last data byte must be transferred by the CPU. */
imx_i2c_write_reg(msgs->buf[msgs->len-1],
i2c_imx, IMX_I2C_I2DR);
- result = i2c_imx_trx_complete(i2c_imx);
+ result = i2c_imx_trx_complete(i2c_imx, false);
if (result)
return result;
@@ -713,7 +746,7 @@ static int i2c_imx_dma_read(struct imx_i2c_struct *i2c_imx,
msgs->buf[msgs->len-2] = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2DR);
/* read n byte data */
- result = i2c_imx_trx_complete(i2c_imx);
+ result = i2c_imx_trx_complete(i2c_imx, false);
if (result)
return result;
@@ -726,7 +759,7 @@ static int i2c_imx_dma_read(struct imx_i2c_struct *i2c_imx,
temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
temp &= ~(I2CR_MSTA | I2CR_MTX);
imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
- i2c_imx_bus_busy(i2c_imx, 0);
+ i2c_imx_bus_busy(i2c_imx, 0, false);
i2c_imx->stopped = 1;
} else {
/*
@@ -745,7 +778,7 @@ static int i2c_imx_dma_read(struct imx_i2c_struct *i2c_imx,
return 0;
}
-static int i2c_imx_write(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs)
+static int i2c_imx_write(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs, bool polling)
{
int i, result;
@@ -754,7 +787,7 @@ static int i2c_imx_write(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs)
/* write slave address */
imx_i2c_write_reg(i2c_8bit_addr_from_msg(msgs), i2c_imx, IMX_I2C_I2DR);
- result = i2c_imx_trx_complete(i2c_imx);
+ result = i2c_imx_trx_complete(i2c_imx, polling);
if (result)
return result;
result = i2c_imx_acked(i2c_imx);
@@ -768,7 +801,7 @@ static int i2c_imx_write(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs)
"<%s> write byte: B%d=0x%X\n",
__func__, i, msgs->buf[i]);
imx_i2c_write_reg(msgs->buf[i], i2c_imx, IMX_I2C_I2DR);
- result = i2c_imx_trx_complete(i2c_imx);
+ result = i2c_imx_trx_complete(i2c_imx, polling);
if (result)
return result;
result = i2c_imx_acked(i2c_imx);
@@ -778,7 +811,7 @@ static int i2c_imx_write(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs)
return 0;
}
-static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs, bool is_lastmsg)
+static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs, bool is_lastmsg, bool polling)
{
int i, result;
unsigned int temp;
@@ -790,7 +823,7 @@ static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs, bo
/* write slave address */
imx_i2c_write_reg(i2c_8bit_addr_from_msg(msgs), i2c_imx, IMX_I2C_I2DR);
- result = i2c_imx_trx_complete(i2c_imx);
+ result = i2c_imx_trx_complete(i2c_imx, polling);
if (result)
return result;
result = i2c_imx_acked(i2c_imx);
@@ -814,14 +847,14 @@ static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs, bo
dev_dbg(&i2c_imx->adapter.dev, "<%s> read data\n", __func__);
- if (i2c_imx->dma && msgs->len >= DMA_THRESHOLD && !block_data)
+ if (i2c_imx->dma && msgs->len >= DMA_THRESHOLD && !block_data && !polling)
return i2c_imx_dma_read(i2c_imx, msgs, is_lastmsg);
/* read data */
for (i = 0; i < msgs->len; i++) {
u8 len = 0;
- result = i2c_imx_trx_complete(i2c_imx);
+ result = i2c_imx_trx_complete(i2c_imx, polling);
if (result)
return result;
/*
@@ -849,7 +882,7 @@ static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs, bo
temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
temp &= ~(I2CR_MSTA | I2CR_MTX);
imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
- i2c_imx_bus_busy(i2c_imx, 0);
+ i2c_imx_bus_busy(i2c_imx, 0, polling);
i2c_imx->stopped = 1;
} else {
/*
@@ -888,6 +921,7 @@ static int i2c_imx_xfer(struct i2c_adapter *adapter,
int result;
bool is_lastmsg = false;
struct imx_i2c_struct *i2c_imx = i2c_get_adapdata(adapter);
+ bool polling = in_atomic() || irqs_disabled();
dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__);
@@ -896,11 +930,11 @@ static int i2c_imx_xfer(struct i2c_adapter *adapter,
goto out;
/* Start I2C transfer */
- result = i2c_imx_start(i2c_imx);
+ result = i2c_imx_start(i2c_imx, polling);
if (result) {
if (i2c_imx->adapter.bus_recovery_info) {
i2c_recover_bus(&i2c_imx->adapter);
- result = i2c_imx_start(i2c_imx);
+ result = i2c_imx_start(i2c_imx, polling);
}
}
@@ -918,7 +952,7 @@ static int i2c_imx_xfer(struct i2c_adapter *adapter,
temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
temp |= I2CR_RSTA;
imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
- result = i2c_imx_bus_busy(i2c_imx, 1);
+ result = i2c_imx_bus_busy(i2c_imx, 1, polling);
if (result)
goto fail0;
}
@@ -942,13 +976,17 @@ static int i2c_imx_xfer(struct i2c_adapter *adapter,
(temp & I2SR_SRW ? 1 : 0), (temp & I2SR_IIF ? 1 : 0),
(temp & I2SR_RXAK ? 1 : 0));
#endif
- if (msgs[i].flags & I2C_M_RD)
- result = i2c_imx_read(i2c_imx, &msgs[i], is_lastmsg);
- else {
- if (i2c_imx->dma && msgs[i].len >= DMA_THRESHOLD)
- result = i2c_imx_dma_write(i2c_imx, &msgs[i]);
- else
- result = i2c_imx_write(i2c_imx, &msgs[i]);
+ if (msgs[i].flags & I2C_M_RD) {
+ result = i2c_imx_read(i2c_imx, &msgs[i], is_lastmsg, polling);
+ } else {
+ if (!polling) {
+ if (i2c_imx->dma && msgs[i].len >= DMA_THRESHOLD)
+ result = i2c_imx_dma_write(i2c_imx, &msgs[i]);
+ else
+ result = i2c_imx_write(i2c_imx, &msgs[i], polling);
+ } else {
+ result = i2c_imx_write(i2c_imx, &msgs[i], polling);
+ }
}
if (result)
goto fail0;
@@ -956,7 +994,7 @@ static int i2c_imx_xfer(struct i2c_adapter *adapter,
fail0:
/* Stop I2C transfer */
- i2c_imx_stop(i2c_imx);
+ i2c_imx_stop(i2c_imx, polling);
pm_runtime_mark_last_busy(i2c_imx->adapter.dev.parent);
pm_runtime_put_autosuspend(i2c_imx->adapter.dev.parent);
@@ -1088,6 +1126,9 @@ static int i2c_imx_probe(struct platform_device *pdev)
i2c_imx->adapter.dev.of_node = pdev->dev.of_node;
i2c_imx->base = base;
+ /* Drivers supports IRQ less operations */
+ i2c_adapter_irq_safe(&i2c_imx->adapter);
+
/* Get I2C clock */
i2c_imx->clk = devm_clk_get(&pdev->dev, NULL);
if (IS_ERR(i2c_imx->clk)) {
@@ -1118,6 +1159,14 @@ static int i2c_imx_probe(struct platform_device *pdev)
/* Set up platform driver data */
platform_set_drvdata(pdev, i2c_imx);
+ /*
+ * Driver's PM callbacks are safe to be called in IRQ disabled
+ * contexts. Providing this information to the PM subsystem is required
+ * for the 'master_xfer' implementation that calls PM routines in IRQ
+ * disabled/atomic contexts, too.
+ */
+ pm_runtime_irq_safe(&pdev->dev);
+
pm_runtime_set_autosuspend_delay(&pdev->dev, I2C_PM_TIMEOUT);
pm_runtime_use_autosuspend(&pdev->dev);
pm_runtime_set_active(&pdev->dev);
--
2.16.4
