[PATCH 02/32] spi: dw: Add support for 32-bits ctrlr0 layout

Damien Le Moal
2020-11-07T08:14:31Z

Synopsis DesignWare DW_apb_ssi version 4 defines a 32-bit layout of
the ctrlr0 register for SPI masters. The layout of ctrlr0 is:

| 31 .. 23 | 22 .. 21 | 20 .. 16 |
| other stuff | spi_frf | dfs_32 |

| 15 .. 10 | 9 .. 8 | 7 .. 6 | 5 .. 4 | 3 .. 0 |
| other stuff | tmod | mode | frf | dfs |

Th main difference of this layout with the 16-bits version is the data
frame format field which resides in bits 16..20 instead of bits 3..0.

Introduce the DW SPI capability flag DW_SPI_CAP_DFS_32 to let a
platform signal that this layout is in use. Modify
dw_spi_update_config() to test this capability flag to set the data
frame format field at the correct register location.

Suggested-by: Sean Anderson <seanga2@gmail.com>
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
---
drivers/spi/spi-dw-core.c | 8 ++++++--
drivers/spi/spi-dw.h | 9 +++++++++
2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/drivers/spi/spi-dw-core.c b/drivers/spi/spi-dw-core.c
index 2e50cc0a9291..841c85247f01 100644
--- a/drivers/spi/spi-dw-core.c
+++ b/drivers/spi/spi-dw-core.c
@@ -311,8 +311,12 @@ void dw_spi_update_config(struct dw_spi *dws, struct spi_device *spi,
u32 speed_hz;
u16 clk_div;

- /* CTRLR0[ 4/3: 0] Data Frame Size */
- cr0 |= (cfg->dfs - 1);
+ if (!(dws->caps & DW_SPI_CAP_DFS_32))
+ /* CTRLR0[ 4/3: 0] Data Frame Size */
+ cr0 |= (cfg->dfs - 1);
+ else
+ /* CTRLR0[20: 16] Data Frame Size */
+ cr0 |= (cfg->dfs - 1) << DWC_APB_CTRLR0_32_DFS_OFFSET;

if (!(dws->caps & DW_SPI_CAP_DWC_SSI))
/* CTRLR0[ 9:8] Transfer Mode */
diff --git a/drivers/spi/spi-dw.h b/drivers/spi/spi-dw.h
index faf40cb66498..48a11a51a407 100644
--- a/drivers/spi/spi-dw.h
+++ b/drivers/spi/spi-dw.h
@@ -9,6 +9,7 @@
#include <linux/io.h>
#include <linux/scatterlist.h>
#include <linux/spi/spi-mem.h>
+#include <linux/bitfield.h>

/* Register offsets */
#define DW_SPI_CTRLR0 0x00
@@ -72,6 +73,13 @@
#define DWC_SSI_CTRLR0_FRF_OFFSET 6
#define DWC_SSI_CTRLR0_DFS_OFFSET 0

+/*
+ * Bit fields in CTRLR0 for DWC_apb_ssi v4 32-bits ctrlr0.
+ * Based on DW_apb_ssi Databook v4.02a.
+ */
+#define DWC_APB_CTRLR0_32_DFS_OFFSET 16
+#define DWC_APB_CTRLR0_32_DFS_MASK GENMASK(20, 16)
+
/*
* For Keem Bay, CTRLR0[31] is used to select controller mode.
* 0: SSI is slave
@@ -121,6 +129,7 @@ enum dw_ssi_type {
#define DW_SPI_CAP_CS_OVERRIDE BIT(0)
#define DW_SPI_CAP_KEEMBAY_MST BIT(1)
#define DW_SPI_CAP_DWC_SSI BIT(2)
+#define DW_SPI_CAP_DFS_32 BIT(3)

/* Slave spi_transfer/spi_mem_op related */
struct dw_spi_cfg {
--
2.28.0