Allow SoCs that require 32 bits register accesses to write data in
chunks of 8 or 16 bits. One SoC that requires 32 bit register accesses
is the google gs101. The operation is rare, thus open code it in the
driver rather than making it generic (through asm-generic/io.h).
Signed-off-by: Tudor Ambarus <tudor.ambarus@xxxxxxxxxx>
---
drivers/spi/spi-s3c64xx.c | 36 ++++++++++++++++++++++++++++++++++--
1 file changed, 34 insertions(+), 2 deletions(-)
diff --git a/drivers/spi/spi-s3c64xx.c b/drivers/spi/spi-s3c64xx.c
index eb79c6e4f509..014fcc933c90 100644
--- a/drivers/spi/spi-s3c64xx.c
+++ b/drivers/spi/spi-s3c64xx.c
@@ -142,6 +142,7 @@ struct s3c64xx_spi_dma_data {
* prescaler unit.
* @clk_ioclk: True if clock is present on this device
* @has_loopback: True if loopback mode can be supported
+ * @use_32bit_io: True if the SoC allows only 32-bit register accesses.
*
* The Samsung s3c64xx SPI controller are used on various Samsung SoC's but
* differ in some aspects such as the size of the fifo and spi bus clock
@@ -158,6 +159,7 @@ struct s3c64xx_spi_port_config {
bool clk_from_cmu;
bool clk_ioclk;
bool has_loopback;
+ bool use_32bit_io;
};
/**
@@ -414,6 +416,30 @@ static bool s3c64xx_spi_can_dma(struct spi_controller *host,
}
+static void s3c64xx_iowrite8_32_rep(volatile void __iomem *addr,
+ const void *buffer, unsigned int count)
+{
+ if (count) {
+ const u8 *buf = buffer;
+
+ do {
+ __raw_writel(*buf++, addr);
+ } while (--count);
+ }
+}
+
+static void s3c64xx_iowrite16_32_rep(volatile void __iomem *addr,
+ const void *buffer, unsigned int count)
+{
+ if (count) {
+ const u16 *buf = buffer;
+
+ do {
+ __raw_writel(*buf++, addr);
+ } while (--count);
+ }
+}
+
static void s3c64xx_iowrite_rep(const struct s3c64xx_spi_driver_data *sdd,
struct spi_transfer *xfer)
{
@@ -426,10 +452,16 @@ static void s3c64xx_iowrite_rep(const struct s3c64xx_spi_driver_data *sdd,
iowrite32_rep(addr, buf, len / 4);
break;
case 16:
- iowrite16_rep(addr, buf, len / 2);
+ if (sdd->port_conf->use_32bit_io)
+ s3c64xx_iowrite16_32_rep(addr, buf, len / 2);
+ else
+ iowrite16_rep(addr, buf, len / 2);
break;
default:
- iowrite8_rep(addr, buf, len);
+ if (sdd->port_conf->use_32bit_io)
+ s3c64xx_iowrite8_32_rep(addr, buf, len);
+ else
+ iowrite8_rep(addr, buf, len);
break;
}
}
--
2.43.0.687.g38aa6559b0-goog
