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Subject[PATCH v1 13/14] spi: rockchip: support 4bit words
Date
From: Emil Renner Berthing <kernel@esmil.dk>

The hardware supports 4, 8 and 16bit spi words,
so add the missing support for 4bit words.

Signed-off-by: Emil Renner Berthing <kernel@esmil.dk>
---
drivers/spi/spi-rockchip.c | 41 +++++++++++++++++++++++++++-----------
1 file changed, 29 insertions(+), 12 deletions(-)

diff --git a/drivers/spi/spi-rockchip.c b/drivers/spi/spi-rockchip.c
index 1297f081818d..9e47e81553a1 100644
--- a/drivers/spi/spi-rockchip.c
+++ b/drivers/spi/spi-rockchip.c
@@ -54,6 +54,9 @@

/* Bit fields in CTRLR0 */
#define CR0_DFS_OFFSET 0
+#define CR0_DFS_4BIT 0x0
+#define CR0_DFS_8BIT 0x1
+#define CR0_DFS_16BIT 0x2

#define CR0_CFS_OFFSET 2

@@ -464,15 +467,14 @@ static void rockchip_spi_config(struct rockchip_spi *rs,
struct spi_device *spi, struct spi_transfer *xfer,
bool use_dma)
{
- u32 dmacr = 0;
-
u32 cr0 = CR0_FRF_SPI << CR0_FRF_OFFSET
| CR0_BHT_8BIT << CR0_BHT_OFFSET
| CR0_SSD_ONE << CR0_SSD_OFFSET
| CR0_EM_BIG << CR0_EM_OFFSET;
+ u32 cr1;
+ u32 dmacr = 0;

cr0 |= rs->rsd << CR0_RSD_OFFSET;
- cr0 |= (rs->n_bytes << CR0_DFS_OFFSET);
cr0 |= (spi->mode & 0x3U) << CR0_SCPH_OFFSET;

if (xfer->rx_buf && xfer->tx_buf)
@@ -482,6 +484,27 @@ static void rockchip_spi_config(struct rockchip_spi *rs,
else if (use_dma)
cr0 |= CR0_XFM_TO << CR0_XFM_OFFSET;

+ switch (xfer->bits_per_word) {
+ case 4:
+ cr0 |= CR0_DFS_4BIT << CR0_DFS_OFFSET;
+ cr1 = xfer->len - 1;
+ break;
+ case 8:
+ cr0 |= CR0_DFS_8BIT << CR0_DFS_OFFSET;
+ cr1 = xfer->len - 1;
+ break;
+ case 16:
+ cr0 |= CR0_DFS_16BIT << CR0_DFS_OFFSET;
+ cr1 = xfer->len / 2 - 1;
+ break;
+ default:
+ /* we only whitelist 4, 8 and 16 bit words in
+ * master->bits_per_word_mask, so this shouldn't
+ * happen
+ */
+ unreachable();
+ }
+
if (use_dma) {
if (xfer->tx_buf)
dmacr |= TF_DMA_EN;
@@ -490,13 +513,7 @@ static void rockchip_spi_config(struct rockchip_spi *rs,
}

writel_relaxed(cr0, rs->regs + ROCKCHIP_SPI_CTRLR0);
-
- if (rs->n_bytes == 1)
- writel_relaxed(xfer->len - 1, rs->regs + ROCKCHIP_SPI_CTRLR1);
- else if (rs->n_bytes == 2)
- writel_relaxed((xfer->len / 2) - 1, rs->regs + ROCKCHIP_SPI_CTRLR1);
- else
- writel_relaxed((xfer->len * 2) - 1, rs->regs + ROCKCHIP_SPI_CTRLR1);
+ writel_relaxed(cr1, rs->regs + ROCKCHIP_SPI_CTRLR1);

/* unfortunately setting the fifo threshold level to generate an
* interrupt exactly when the fifo is full doesn't seem to work,
@@ -545,7 +562,7 @@ static int rockchip_spi_transfer_one(
return -EINVAL;
}

- rs->n_bytes = xfer->bits_per_word >> 3;
+ rs->n_bytes = xfer->bits_per_word <= 8 ? 1 : 2;

use_dma = master->can_dma ? master->can_dma(master, spi, xfer) : false;

@@ -667,7 +684,7 @@ static int rockchip_spi_probe(struct platform_device *pdev)
master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_LOOP;
master->num_chipselect = ROCKCHIP_SPI_MAX_CS_NUM;
master->dev.of_node = pdev->dev.of_node;
- master->bits_per_word_mask = SPI_BPW_MASK(16) | SPI_BPW_MASK(8);
+ master->bits_per_word_mask = SPI_BPW_MASK(16) | SPI_BPW_MASK(8) | SPI_BPW_MASK(4);
master->min_speed_hz = rs->freq / BAUDR_SCKDV_MAX;
master->max_speed_hz = min(rs->freq / BAUDR_SCKDV_MIN, MAX_SCLK_OUT);

--
2.19.1
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