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authorMichael van der Westhuizen <michael@smart-africa.com>2015-08-18 22:21:53 +0200
committerMark Brown <broonie@kernel.org>2015-08-21 10:25:28 -0700
commitc4fe57f76269dbb2af135071513f260ca40229a3 (patch)
tree60afe5453b7602b4cc2fae53ba75236bce2544e1 /drivers/spi
parent4b226fbde68b8bfb66452067523a677b8e6492fa (diff)
downloadlinux-c4fe57f76269dbb2af135071513f260ca40229a3.tar.bz2
spi: dw: Allow interface drivers to limit data I/O to word sizes
The commit dd11444327ce ("spi: dw-spi: Convert 16bit accesses to 32bit accesses") changed all 16bit accesses in the DW_apb_ssi driver to 32bit. This, unfortunately, breaks data register access on picoXcell, where the DW IP needs data register accesses to be word accesses (all other accesses appear to be OK). This change introduces a new master variable to allow interface drivers to specify that 16bit data transfer I/O is required. This change also introduces the ability to set this variable via device tree bindings in the MMIO interface driver. Both the core and the MMIO interface driver default to the current 32bit behaviour. Before this change, on a picoXcell pc3x3: spi_master spi32766: interrupt_transfer: fifo overrun/underrun m25p80 spi32766.0: error -5 reading 9f m25p80: probe of spi32766.0 failed with error -5 After this change: m25p80 spi32766.0: m25p40 (512 Kbytes) Fixes: dd11444327ce ("spi: dw-spi: Convert 16bit accesses to 32bit accesses") Signed-off-by: Michael van der Westhuizen <michael@smart-africa.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Mark Brown <broonie@kernel.org>
Diffstat (limited to 'drivers/spi')
-rw-r--r--drivers/spi/spi-dw-mmio.c3
-rw-r--r--drivers/spi/spi-dw.c4
-rw-r--r--drivers/spi/spi-dw.h35
3 files changed, 40 insertions, 2 deletions
diff --git a/drivers/spi/spi-dw-mmio.c b/drivers/spi/spi-dw-mmio.c
index eb03e1215195..7edede6e024b 100644
--- a/drivers/spi/spi-dw-mmio.c
+++ b/drivers/spi/spi-dw-mmio.c
@@ -74,6 +74,9 @@ static int dw_spi_mmio_probe(struct platform_device *pdev)
dws->max_freq = clk_get_rate(dwsmmio->clk);
+ of_property_read_u32(pdev->dev.of_node, "reg-io-width",
+ &dws->reg_io_width);
+
num_cs = 4;
if (pdev->dev.of_node)
diff --git a/drivers/spi/spi-dw.c b/drivers/spi/spi-dw.c
index 8d67d03c71eb..4fbfcdc5cb24 100644
--- a/drivers/spi/spi-dw.c
+++ b/drivers/spi/spi-dw.c
@@ -194,7 +194,7 @@ static void dw_writer(struct dw_spi *dws)
else
txw = *(u16 *)(dws->tx);
}
- dw_writel(dws, DW_SPI_DR, txw);
+ dw_write_io_reg(dws, DW_SPI_DR, txw);
dws->tx += dws->n_bytes;
}
}
@@ -205,7 +205,7 @@ static void dw_reader(struct dw_spi *dws)
u16 rxw;
while (max--) {
- rxw = dw_readl(dws, DW_SPI_DR);
+ rxw = dw_read_io_reg(dws, DW_SPI_DR);
/* Care rx only if the transfer's original "rx" is not null */
if (dws->rx_end - dws->len) {
if (dws->n_bytes == 1)
diff --git a/drivers/spi/spi-dw.h b/drivers/spi/spi-dw.h
index 6c91391c1a4f..b75ed327d5a2 100644
--- a/drivers/spi/spi-dw.h
+++ b/drivers/spi/spi-dw.h
@@ -109,6 +109,7 @@ struct dw_spi {
u32 fifo_len; /* depth of the FIFO buffer */
u32 max_freq; /* max bus freq supported */
+ u32 reg_io_width; /* DR I/O width in bytes */
u16 bus_num;
u16 num_cs; /* supported slave numbers */
@@ -145,11 +146,45 @@ static inline u32 dw_readl(struct dw_spi *dws, u32 offset)
return __raw_readl(dws->regs + offset);
}
+static inline u16 dw_readw(struct dw_spi *dws, u32 offset)
+{
+ return __raw_readw(dws->regs + offset);
+}
+
static inline void dw_writel(struct dw_spi *dws, u32 offset, u32 val)
{
__raw_writel(val, dws->regs + offset);
}
+static inline void dw_writew(struct dw_spi *dws, u32 offset, u16 val)
+{
+ __raw_writew(val, dws->regs + offset);
+}
+
+static inline u32 dw_read_io_reg(struct dw_spi *dws, u32 offset)
+{
+ switch (dws->reg_io_width) {
+ case 2:
+ return dw_readw(dws, offset);
+ case 4:
+ default:
+ return dw_readl(dws, offset);
+ }
+}
+
+static inline void dw_write_io_reg(struct dw_spi *dws, u32 offset, u32 val)
+{
+ switch (dws->reg_io_width) {
+ case 2:
+ dw_writew(dws, offset, val);
+ break;
+ case 4:
+ default:
+ dw_writel(dws, offset, val);
+ break;
+ }
+}
+
static inline void spi_enable_chip(struct dw_spi *dws, int enable)
{
dw_writel(dws, DW_SPI_SSIENR, (enable ? 1 : 0));