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authorAmit Kumar Mahapatra <amit.kumar-mahapatra@amd.com>2023-11-25 12:21:30 +0300
committerMark Brown <broonie@kernel.org>2023-12-07 19:23:20 +0300
commit4d8ff6b0991d5e86b17b235fc46ec62e9195cb9b (patch)
tree88f42ec868bb5d4891035f5559b08ee56decf1a4 /include/linux/spi
parentf05e2f61fe88092e0d341ea27644a84e3386358d (diff)
downloadlinux-4d8ff6b0991d5e86b17b235fc46ec62e9195cb9b.tar.xz
spi: Add multi-cs memories support in SPI core
AMD-Xilinx GQSPI controller has two advanced mode that allows the controller to consider two flashes as one single device. One of these two mode is the parallel mode in which each byte of data is stored in both devices, the even bits in the lower flash & the odd bits in the upper flash. The byte split is automatically handled by the QSPI controller. The other mode is the stacked mode in which both the flashes share the same SPI bus but each of the device contain half of the data. In this mode, the controller does not follow CS requests but instead internally wires the two CS levels with the value of the most significant address bit. For supporting both these modes SPI core need to be updated for providing multiple CS for a single SPI device. For adding multi CS support the SPI device need to be aware of all the CS values. So, the "chip_select" member in the spi_device structure is now an array that holds all the CS values. spi_device structure now has a "cs_index_mask" member. This acts as an index to the chip_select array. If nth bit of spi->cs_index_mask is set then the driver would assert spi->chip_select[n]. In parallel mode all the chip selects are asserted/de-asserted simultaneously and each byte of data is stored in both devices, the even bits in one, the odd bits in the other. The split is automatically handled by the GQSPI controller. The GQSPI controller supports a maximum of two flashes connected in parallel mode. A SPI_CONTROLLER_MULTI_CS flag bit is added in the spi controller flags, through ctlr->flags the spi core will make sure that the controller is capable of handling multiple chip selects at once. For supporting multiple CS via GPIO the cs_gpiod member of the spi_device structure is now an array that holds the gpio descriptor for each chipselect. CS GPIO is not tested on our hardware, but it has been tested by @Stefan https://lore.kernel.org/all/005001da1efc$619ad5a0$24d080e0$@opensource.cirrus.com/ Signed-off-by: Amit Kumar Mahapatra <amit.kumar-mahapatra@amd.com> Tested-by: Stefan Binding <sbinding@opensource.cirrus.com> Link: https://lore.kernel.org/r/20231125092137.2948-4-amit.kumar-mahapatra@amd.com Signed-off-by: Mark Brown <broonie@kernel.org>
Diffstat (limited to 'include/linux/spi')
-rw-r--r--include/linux/spi/spi.h51
1 files changed, 41 insertions, 10 deletions
diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index 255a0562aea5..50622054b6af 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -20,6 +20,9 @@
#include <uapi/linux/spi/spi.h>
+/* Max no. of CS supported per spi device */
+#define SPI_CS_CNT_MAX 4
+
struct dma_chan;
struct software_node;
struct ptp_system_timestamp;
@@ -132,7 +135,8 @@ extern void spi_transfer_cs_change_delay_exec(struct spi_message *msg,
* @max_speed_hz: Maximum clock rate to be used with this chip
* (on this board); may be changed by the device's driver.
* The spi_transfer.speed_hz can override this for each transfer.
- * @chip_select: Chipselect, distinguishing chips handled by @controller.
+ * @chip_select: Array of physical chipselect, spi->chipselect[i] gives
+ * the corresponding physical CS for logical CS i.
* @mode: The spi mode defines how data is clocked out and in.
* This may be changed by the device's driver.
* The "active low" default for chipselect mode can be overridden
@@ -157,8 +161,8 @@ extern void spi_transfer_cs_change_delay_exec(struct spi_message *msg,
* the device will bind to the named driver and only the named driver.
* Do not set directly, because core frees it; use driver_set_override() to
* set or clear it.
- * @cs_gpiod: GPIO descriptor of the chipselect line (optional, NULL when
- * not using a GPIO line)
+ * @cs_gpiod: Array of GPIO descriptors of the corresponding chipselect lines
+ * (optional, NULL when not using a GPIO line)
* @word_delay: delay to be inserted between consecutive
* words of a transfer
* @cs_setup: delay to be introduced by the controller after CS is asserted
@@ -167,6 +171,7 @@ extern void spi_transfer_cs_change_delay_exec(struct spi_message *msg,
* deasserted. If @cs_change_delay is used from @spi_transfer, then the
* two delays will be added up.
* @pcpu_statistics: statistics for the spi_device
+ * @cs_index_mask: Bit mask of the active chipselect(s) in the chipselect array
*
* A @spi_device is used to interchange data between an SPI slave
* (usually a discrete chip) and CPU memory.
@@ -182,7 +187,7 @@ struct spi_device {
struct spi_controller *controller;
struct spi_controller *master; /* Compatibility layer */
u32 max_speed_hz;
- u8 chip_select;
+ u8 chip_select[SPI_CS_CNT_MAX];
u8 bits_per_word;
bool rt;
#define SPI_NO_TX BIT(31) /* No transmit wire */
@@ -213,7 +218,7 @@ struct spi_device {
void *controller_data;
char modalias[SPI_NAME_SIZE];
const char *driver_override;
- struct gpio_desc *cs_gpiod; /* Chip select GPIO descriptor */
+ struct gpio_desc *cs_gpiod[SPI_CS_CNT_MAX]; /* Chip select gpio desc */
struct spi_delay word_delay; /* Inter-word delay */
/* CS delays */
struct spi_delay cs_setup;
@@ -223,6 +228,13 @@ struct spi_device {
/* The statistics */
struct spi_statistics __percpu *pcpu_statistics;
+ /* Bit mask of the chipselect(s) that the driver need to use from
+ * the chipselect array.When the controller is capable to handle
+ * multiple chip selects & memories are connected in parallel
+ * then more than one bit need to be set in cs_index_mask.
+ */
+ u32 cs_index_mask : SPI_CS_CNT_MAX;
+
/*
* Likely need more hooks for more protocol options affecting how
* the controller talks to each chip, like:
@@ -279,22 +291,33 @@ static inline void *spi_get_drvdata(const struct spi_device *spi)
static inline u8 spi_get_chipselect(const struct spi_device *spi, u8 idx)
{
- return spi->chip_select;
+ return spi->chip_select[idx];
}
static inline void spi_set_chipselect(struct spi_device *spi, u8 idx, u8 chipselect)
{
- spi->chip_select = chipselect;
+ spi->chip_select[idx] = chipselect;
}
static inline struct gpio_desc *spi_get_csgpiod(const struct spi_device *spi, u8 idx)
{
- return spi->cs_gpiod;
+ return spi->cs_gpiod[idx];
}
static inline void spi_set_csgpiod(struct spi_device *spi, u8 idx, struct gpio_desc *csgpiod)
{
- spi->cs_gpiod = csgpiod;
+ spi->cs_gpiod[idx] = csgpiod;
+}
+
+static inline bool spi_is_csgpiod(struct spi_device *spi)
+{
+ u8 idx;
+
+ for (idx = 0; idx < SPI_CS_CNT_MAX; idx++) {
+ if (spi_get_csgpiod(spi, idx))
+ return true;
+ }
+ return false;
}
/**
@@ -399,6 +422,8 @@ extern struct spi_device *spi_new_ancillary_device(struct spi_device *spi, u8 ch
* @bus_lock_spinlock: spinlock for SPI bus locking
* @bus_lock_mutex: mutex for exclusion of multiple callers
* @bus_lock_flag: indicates that the SPI bus is locked for exclusive use
+ * @multi_cs_cap: indicates that the SPI Controller can assert/de-assert
+ * more than one chip select at once.
* @setup: updates the device mode and clocking records used by a
* device's SPI controller; protocol code may call this. This
* must fail if an unrecognized or unsupported mode is requested.
@@ -567,6 +592,11 @@ struct spi_controller {
#define SPI_CONTROLLER_MUST_TX BIT(4) /* Requires tx */
#define SPI_CONTROLLER_GPIO_SS BIT(5) /* GPIO CS must select slave */
#define SPI_CONTROLLER_SUSPENDED BIT(6) /* Currently suspended */
+ /*
+ * The spi-controller has multi chip select capability and can
+ * assert/de-assert more than one chip select at once.
+ */
+#define SPI_CONTROLLER_MULTI_CS BIT(7)
/* Flag indicating if the allocation of this struct is devres-managed */
bool devm_allocated;
@@ -677,7 +707,8 @@ struct spi_controller {
bool rt;
bool auto_runtime_pm;
bool cur_msg_mapped;
- char last_cs;
+ char last_cs[SPI_CS_CNT_MAX];
+ char last_cs_index_mask;
bool last_cs_mode_high;
bool fallback;
struct completion xfer_completion;