[PATCH AUTOSEL 5.4 02/35] spi: spi-omap2-mcspi: Support probe deferral for DMA channels

Sasha Levin
2020-03-16T02:40:01Z

From: Vignesh Raghavendra <vigneshr@ti.com>

[ Upstream commit 32f2fc5dc3992b4b60cc6b1a6a31be605cc9c3a2 ]

dma_request_channel() can return -EPROBE_DEFER, if DMA driver is not
ready. Currently driver just falls back to PIO mode on probe deferral.
Fix this by requesting all required channels during probe and
propagating EPROBE_DEFER error code.

Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
Link: https://lore.kernel.org/r/20200204124816.16735-3-vigneshr@ti.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/spi/spi-omap2-mcspi.c | 77 +++++++++++++++++------------------
1 file changed, 38 insertions(+), 39 deletions(-)

diff --git a/drivers/spi/spi-omap2-mcspi.c b/drivers/spi/spi-omap2-mcspi.c
index 8e435da730996..cfb64e5a7d45d 100644
--- a/drivers/spi/spi-omap2-mcspi.c
+++ b/drivers/spi/spi-omap2-mcspi.c
@@ -986,20 +986,12 @@ static int omap2_mcspi_setup_transfer(struct spi_device *spi,
* Note that we currently allow DMA only if we get a channel
* for both rx and tx. Otherwise we'll do PIO for both rx and tx.
*/
-static int omap2_mcspi_request_dma(struct spi_device *spi)
+static int omap2_mcspi_request_dma(struct omap2_mcspi *mcspi,
+ struct omap2_mcspi_dma *mcspi_dma)
{
- struct spi_master *master = spi->master;
- struct omap2_mcspi *mcspi;
- struct omap2_mcspi_dma *mcspi_dma;
int ret = 0;

- mcspi = spi_master_get_devdata(master);
- mcspi_dma = mcspi->dma_channels + spi->chip_select;
-
- init_completion(&mcspi_dma->dma_rx_completion);
- init_completion(&mcspi_dma->dma_tx_completion);
-
- mcspi_dma->dma_rx = dma_request_chan(&master->dev,
+ mcspi_dma->dma_rx = dma_request_chan(mcspi->dev,
mcspi_dma->dma_rx_ch_name);
if (IS_ERR(mcspi_dma->dma_rx)) {
ret = PTR_ERR(mcspi_dma->dma_rx);
@@ -1007,7 +999,7 @@ static int omap2_mcspi_request_dma(struct spi_device *spi)
goto no_dma;
}

- mcspi_dma->dma_tx = dma_request_chan(&master->dev,
+ mcspi_dma->dma_tx = dma_request_chan(mcspi->dev,
mcspi_dma->dma_tx_ch_name);
if (IS_ERR(mcspi_dma->dma_tx)) {
ret = PTR_ERR(mcspi_dma->dma_tx);
@@ -1016,20 +1008,40 @@ static int omap2_mcspi_request_dma(struct spi_device *spi)
mcspi_dma->dma_rx = NULL;
}

+ init_completion(&mcspi_dma->dma_rx_completion);
+ init_completion(&mcspi_dma->dma_tx_completion);
+
no_dma:
return ret;
}

+static void omap2_mcspi_release_dma(struct spi_master *master)
+{
+ struct omap2_mcspi *mcspi = spi_master_get_devdata(master);
+ struct omap2_mcspi_dma *mcspi_dma;
+ int i;
+
+ for (i = 0; i < master->num_chipselect; i++) {
+ mcspi_dma = &mcspi->dma_channels[i];
+
+ if (mcspi_dma->dma_rx) {
+ dma_release_channel(mcspi_dma->dma_rx);
+ mcspi_dma->dma_rx = NULL;
+ }
+ if (mcspi_dma->dma_tx) {
+ dma_release_channel(mcspi_dma->dma_tx);
+ mcspi_dma->dma_tx = NULL;
+ }
+ }
+}
+
static int omap2_mcspi_setup(struct spi_device *spi)
{
int ret;
struct omap2_mcspi *mcspi = spi_master_get_devdata(spi->master);
struct omap2_mcspi_regs *ctx = &mcspi->ctx;
- struct omap2_mcspi_dma *mcspi_dma;
struct omap2_mcspi_cs *cs = spi->controller_state;

- mcspi_dma = &mcspi->dma_channels[spi->chip_select];
-
if (!cs) {
cs = kzalloc(sizeof *cs, GFP_KERNEL);
if (!cs)
@@ -1054,13 +1066,6 @@ static int omap2_mcspi_setup(struct spi_device *spi)
}
}

- if (!mcspi_dma->dma_rx || !mcspi_dma->dma_tx) {
- ret = omap2_mcspi_request_dma(spi);
- if (ret)
- dev_warn(&spi->dev, "not using DMA for McSPI (%d)\n",
- ret);
- }
-
ret = pm_runtime_get_sync(mcspi->dev);
if (ret < 0) {
pm_runtime_put_noidle(mcspi->dev);
@@ -1077,12 +1082,8 @@ static int omap2_mcspi_setup(struct spi_device *spi)

static void omap2_mcspi_cleanup(struct spi_device *spi)
{
- struct omap2_mcspi *mcspi;
- struct omap2_mcspi_dma *mcspi_dma;
struct omap2_mcspi_cs *cs;

- mcspi = spi_master_get_devdata(spi->master);
-
if (spi->controller_state) {
/* Unlink controller state from context save list */
cs = spi->controller_state;
@@ -1091,19 +1092,6 @@ static void omap2_mcspi_cleanup(struct spi_device *spi)
kfree(cs);
}

- if (spi->chip_select < spi->master->num_chipselect) {
- mcspi_dma = &mcspi->dma_channels[spi->chip_select];
-
- if (mcspi_dma->dma_rx) {
- dma_release_channel(mcspi_dma->dma_rx);
- mcspi_dma->dma_rx = NULL;
- }
- if (mcspi_dma->dma_tx) {
- dma_release_channel(mcspi_dma->dma_tx);
- mcspi_dma->dma_tx = NULL;
- }
- }
-
if (gpio_is_valid(spi->cs_gpio))
gpio_free(spi->cs_gpio);
}
@@ -1314,6 +1302,9 @@ static bool omap2_mcspi_can_dma(struct spi_master *master,
if (spi_controller_is_slave(master))
return true;

+ master->dma_rx = mcspi_dma->dma_rx;
+ master->dma_tx = mcspi_dma->dma_tx;
+
return (xfer->len >= DMA_MIN_BYTES);
}

@@ -1501,6 +1492,11 @@ static int omap2_mcspi_probe(struct platform_device *pdev)
for (i = 0; i < master->num_chipselect; i++) {
sprintf(mcspi->dma_channels[i].dma_rx_ch_name, "rx%d", i);
sprintf(mcspi->dma_channels[i].dma_tx_ch_name, "tx%d", i);
+
+ status = omap2_mcspi_request_dma(mcspi,
+ &mcspi->dma_channels[i]);
+ if (status == -EPROBE_DEFER)
+ goto free_master;
}

status = platform_get_irq(pdev, 0);
@@ -1538,6 +1534,7 @@ static int omap2_mcspi_probe(struct platform_device *pdev)
pm_runtime_put_sync(&pdev->dev);
pm_runtime_disable(&pdev->dev);
free_master:
+ omap2_mcspi_release_dma(master);
spi_master_put(master);
return status;
}
@@ -1547,6 +1544,8 @@ static int omap2_mcspi_remove(struct platform_device *pdev)
struct spi_master *master = platform_get_drvdata(pdev);
struct omap2_mcspi *mcspi = spi_master_get_devdata(master);

+ omap2_mcspi_release_dma(master);
+
pm_runtime_dont_use_autosuspend(mcspi->dev);
pm_runtime_put_sync(mcspi->dev);
pm_runtime_disable(&pdev->dev);
--
2.20.1