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-rw-r--r--drivers/spi/spi_gpio.c101
-rw-r--r--include/linux/spi/spi_gpio.h5
2 files changed, 88 insertions, 18 deletions
diff --git a/drivers/spi/spi_gpio.c b/drivers/spi/spi_gpio.c
index 82b480cc9637..e24a63498acb 100644
--- a/drivers/spi/spi_gpio.c
+++ b/drivers/spi/spi_gpio.c
@@ -167,6 +167,44 @@ static u32 spi_gpio_txrx_word_mode3(struct spi_device *spi,
return bitbang_txrx_be_cpha1(spi, nsecs, 1, 0, word, bits);
}
+/*
+ * These functions do not call setmosi or getmiso if respective flag
+ * (SPI_MASTER_NO_RX or SPI_MASTER_NO_TX) is set, so they are safe to
+ * call when such pin is not present or defined in the controller.
+ * A separate set of callbacks is defined to get highest possible
+ * speed in the generic case (when both MISO and MOSI lines are
+ * available), as optimiser will remove the checks when argument is
+ * constant.
+ */
+
+static u32 spi_gpio_spec_txrx_word_mode0(struct spi_device *spi,
+ unsigned nsecs, u32 word, u8 bits)
+{
+ unsigned flags = spi->master->flags;
+ return bitbang_txrx_be_cpha0(spi, nsecs, 0, flags, word, bits);
+}
+
+static u32 spi_gpio_spec_txrx_word_mode1(struct spi_device *spi,
+ unsigned nsecs, u32 word, u8 bits)
+{
+ unsigned flags = spi->master->flags;
+ return bitbang_txrx_be_cpha1(spi, nsecs, 0, flags, word, bits);
+}
+
+static u32 spi_gpio_spec_txrx_word_mode2(struct spi_device *spi,
+ unsigned nsecs, u32 word, u8 bits)
+{
+ unsigned flags = spi->master->flags;
+ return bitbang_txrx_be_cpha0(spi, nsecs, 1, flags, word, bits);
+}
+
+static u32 spi_gpio_spec_txrx_word_mode3(struct spi_device *spi,
+ unsigned nsecs, u32 word, u8 bits)
+{
+ unsigned flags = spi->master->flags;
+ return bitbang_txrx_be_cpha1(spi, nsecs, 1, flags, word, bits);
+}
+
/*----------------------------------------------------------------------*/
static void spi_gpio_chipselect(struct spi_device *spi, int is_active)
@@ -232,19 +270,30 @@ static int __init spi_gpio_alloc(unsigned pin, const char *label, bool is_in)
}
static int __init
-spi_gpio_request(struct spi_gpio_platform_data *pdata, const char *label)
+spi_gpio_request(struct spi_gpio_platform_data *pdata, const char *label,
+ u16 *res_flags)
{
int value;
/* NOTE: SPI_*_GPIO symbols may reference "pdata" */
- value = spi_gpio_alloc(SPI_MOSI_GPIO, label, false);
- if (value)
- goto done;
+ if (SPI_MOSI_GPIO != SPI_GPIO_NO_MOSI) {
+ value = spi_gpio_alloc(SPI_MOSI_GPIO, label, false);
+ if (value)
+ goto done;
+ } else {
+ /* HW configuration without MOSI pin */
+ *res_flags |= SPI_MASTER_NO_TX;
+ }
- value = spi_gpio_alloc(SPI_MISO_GPIO, label, true);
- if (value)
- goto free_mosi;
+ if (SPI_MISO_GPIO != SPI_GPIO_NO_MISO) {
+ value = spi_gpio_alloc(SPI_MISO_GPIO, label, true);
+ if (value)
+ goto free_mosi;
+ } else {
+ /* HW configuration without MISO pin */
+ *res_flags |= SPI_MASTER_NO_RX;
+ }
value = spi_gpio_alloc(SPI_SCK_GPIO, label, false);
if (value)
@@ -253,9 +302,11 @@ spi_gpio_request(struct spi_gpio_platform_data *pdata, const char *label)
goto done;
free_miso:
- gpio_free(SPI_MISO_GPIO);
+ if (SPI_MISO_GPIO != SPI_GPIO_NO_MISO)
+ gpio_free(SPI_MISO_GPIO);
free_mosi:
- gpio_free(SPI_MOSI_GPIO);
+ if (SPI_MOSI_GPIO != SPI_GPIO_NO_MOSI)
+ gpio_free(SPI_MOSI_GPIO);
done:
return value;
}
@@ -266,6 +317,7 @@ static int __init spi_gpio_probe(struct platform_device *pdev)
struct spi_master *master;
struct spi_gpio *spi_gpio;
struct spi_gpio_platform_data *pdata;
+ u16 master_flags = 0;
pdata = pdev->dev.platform_data;
#ifdef GENERIC_BITBANG
@@ -273,7 +325,7 @@ static int __init spi_gpio_probe(struct platform_device *pdev)
return -ENODEV;
#endif
- status = spi_gpio_request(pdata, dev_name(&pdev->dev));
+ status = spi_gpio_request(pdata, dev_name(&pdev->dev), &master_flags);
if (status < 0)
return status;
@@ -289,6 +341,7 @@ static int __init spi_gpio_probe(struct platform_device *pdev)
if (pdata)
spi_gpio->pdata = *pdata;
+ master->flags = master_flags;
master->bus_num = pdev->id;
master->num_chipselect = SPI_N_CHIPSEL;
master->setup = spi_gpio_setup;
@@ -296,10 +349,18 @@ static int __init spi_gpio_probe(struct platform_device *pdev)
spi_gpio->bitbang.master = spi_master_get(master);
spi_gpio->bitbang.chipselect = spi_gpio_chipselect;
- spi_gpio->bitbang.txrx_word[SPI_MODE_0] = spi_gpio_txrx_word_mode0;
- spi_gpio->bitbang.txrx_word[SPI_MODE_1] = spi_gpio_txrx_word_mode1;
- spi_gpio->bitbang.txrx_word[SPI_MODE_2] = spi_gpio_txrx_word_mode2;
- spi_gpio->bitbang.txrx_word[SPI_MODE_3] = spi_gpio_txrx_word_mode3;
+
+ if ((master_flags & (SPI_MASTER_NO_RX | SPI_MASTER_NO_RX)) == 0) {
+ spi_gpio->bitbang.txrx_word[SPI_MODE_0] = spi_gpio_txrx_word_mode0;
+ spi_gpio->bitbang.txrx_word[SPI_MODE_1] = spi_gpio_txrx_word_mode1;
+ spi_gpio->bitbang.txrx_word[SPI_MODE_2] = spi_gpio_txrx_word_mode2;
+ spi_gpio->bitbang.txrx_word[SPI_MODE_3] = spi_gpio_txrx_word_mode3;
+ } else {
+ spi_gpio->bitbang.txrx_word[SPI_MODE_0] = spi_gpio_spec_txrx_word_mode0;
+ spi_gpio->bitbang.txrx_word[SPI_MODE_1] = spi_gpio_spec_txrx_word_mode1;
+ spi_gpio->bitbang.txrx_word[SPI_MODE_2] = spi_gpio_spec_txrx_word_mode2;
+ spi_gpio->bitbang.txrx_word[SPI_MODE_3] = spi_gpio_spec_txrx_word_mode3;
+ }
spi_gpio->bitbang.setup_transfer = spi_bitbang_setup_transfer;
spi_gpio->bitbang.flags = SPI_CS_HIGH;
@@ -307,8 +368,10 @@ static int __init spi_gpio_probe(struct platform_device *pdev)
if (status < 0) {
spi_master_put(spi_gpio->bitbang.master);
gpio_free:
- gpio_free(SPI_MISO_GPIO);
- gpio_free(SPI_MOSI_GPIO);
+ if (SPI_MISO_GPIO != SPI_GPIO_NO_MISO)
+ gpio_free(SPI_MISO_GPIO);
+ if (SPI_MOSI_GPIO != SPI_GPIO_NO_MOSI)
+ gpio_free(SPI_MOSI_GPIO);
gpio_free(SPI_SCK_GPIO);
spi_master_put(master);
}
@@ -331,8 +394,10 @@ static int __exit spi_gpio_remove(struct platform_device *pdev)
platform_set_drvdata(pdev, NULL);
- gpio_free(SPI_MISO_GPIO);
- gpio_free(SPI_MOSI_GPIO);
+ if (SPI_MISO_GPIO != SPI_GPIO_NO_MISO)
+ gpio_free(SPI_MISO_GPIO);
+ if (SPI_MOSI_GPIO != SPI_GPIO_NO_MOSI)
+ gpio_free(SPI_MOSI_GPIO);
gpio_free(SPI_SCK_GPIO);
return status;
diff --git a/include/linux/spi/spi_gpio.h b/include/linux/spi/spi_gpio.h
index ca6782ee4b9f..369b3d7d5b95 100644
--- a/include/linux/spi/spi_gpio.h
+++ b/include/linux/spi/spi_gpio.h
@@ -29,11 +29,16 @@
* SPI_GPIO_NO_CHIPSELECT to the controller_data:
* .controller_data = (void *) SPI_GPIO_NO_CHIPSELECT;
*
+ * If the MISO or MOSI pin is not available then it should be set to
+ * SPI_GPIO_NO_MISO or SPI_GPIO_NO_MOSI.
+ *
* If the bitbanged bus is later switched to a "native" controller,
* that platform_device and controller_data should be removed.
*/
#define SPI_GPIO_NO_CHIPSELECT ((unsigned long)-1l)
+#define SPI_GPIO_NO_MISO ((unsigned long)-1l)
+#define SPI_GPIO_NO_MOSI ((unsigned long)-1l)
/**
* struct spi_gpio_platform_data - parameter for bitbanged SPI master
generated by cgit (git 2.34.1) at 2024-06-21 17:04:04 +0000