iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

spi: rockchip: precompute rx sample delay

Browse Source 
Now that we no longer potentially change spi clock
at runtime we can precompute the rx sample delay
at probe time rather than for each transfer.

Signed-off-by: Emil Renner Berthing <kernel@esmil.dk>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Emil Renner Berthing 2018-10-31 11:57:08 +01:00 committed by Mark Brown
parent 420b82f842
commit 74b7efa82b
No known key found for this signature in database
GPG Key ID: 24D68B725D5487D0
1 changed files with 18 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

36
drivers/spi/spi-rockchip.c
View File

@ -94,6 +94,7 @@
#define CR0_BHT_8BIT 0x1
#define CR0_RSD_OFFSET 14
#define CR0_RSD_MAX 0x3
#define CR0_FRF_OFFSET 16
#define CR0_FRF_SPI 0x0
@ -179,7 +180,7 @@ struct rockchip_spi {
u32 freq;
u8 n_bytes;
u32 rsd_nsecs;
u8 rsd;
const void *tx;
const void *tx_end;
@ -450,13 +451,13 @@ static void rockchip_spi_config(struct rockchip_spi *rs,
bool use_dma)
{
u32 dmacr = 0;
int rsd = 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;
cr0 |= rs->rsd << CR0_RSD_OFFSET;
cr0 |= (rs->n_bytes << CR0_DFS_OFFSET);
cr0 |= (spi->mode & 0x3U) << CR0_SCPH_OFFSET;
@ -474,20 +475,6 @@ static void rockchip_spi_config(struct rockchip_spi *rs,
dmacr |= RF_DMA_EN;
}
/* Rx sample delay is expressed in parent clock cycles (max 3) */
rsd = DIV_ROUND_CLOSEST(rs->rsd_nsecs * (rs->freq >> 8),
1000000000 >> 8);
if (!rsd && rs->rsd_nsecs) {
pr_warn_once("rockchip-spi: %u Hz are too slow to express %u ns delay\n",
rs->freq, rs->rsd_nsecs);
} else if (rsd > 3) {
rsd = 3;
pr_warn_once("rockchip-spi: %u Hz are too fast to express %u ns delay, clamping at %u ns\n",
rs->freq, rs->rsd_nsecs,
rsd * 1000000000U / rs->freq);
}
cr0 |= rsd << CR0_RSD_OFFSET;
writel_relaxed(cr0, rs->regs + ROCKCHIP_SPI_CTRLR0);
if (rs->n_bytes == 1)
@ -620,8 +607,21 @@ static int rockchip_spi_probe(struct platform_device *pdev)
rs->freq = clk_get_rate(rs->spiclk);
if (!of_property_read_u32(pdev->dev.of_node, "rx-sample-delay-ns",
&rsd_nsecs))
rs->rsd_nsecs = rsd_nsecs;
&rsd_nsecs)) {
/* rx sample delay is expressed in parent clock cycles (max 3) */
u32 rsd = DIV_ROUND_CLOSEST(rsd_nsecs * (rs->freq >> 8),
1000000000 >> 8);
if (!rsd) {
dev_warn(rs->dev, "%u Hz are too slow to express %u ns delay\n",
rs->freq, rsd_nsecs);
} else if (rsd > CR0_RSD_MAX) {
rsd = CR0_RSD_MAX;
dev_warn(rs->dev, "%u Hz are too fast to express %u ns delay, clamping at %u ns\n",
rs->freq, rsd_nsecs,
CR0_RSD_MAX * 1000000000U / rs->freq);
}
rs->rsd = rsd;
}
rs->fifo_len = get_fifo_len(rs);
if (!rs->fifo_len) {