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mmc: sdhci-of-aspeed: Add AST2600 bus clock support 

The AST2600 can achieve HS200 speeds with a change to the bus clock
divisor behaviour. The divisor can also be more accurate with respect
to the requested clock rate, but keep the one-hot behaviour for
backwards compatibility with the AST2400 and AST2500.

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Link: https://lore.kernel.org/r/20210114031433.2388532-4-andrew@aj.id.au
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
This commit is contained in:
Andrew Jeffery 2021-01-14 13:44:30 +10:30 committed by Ulf Hansson
parent 2fc88f9235
commit 0c53dc321a
1 changed files with 33 additions and 4 deletions
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37
drivers/mmc/host/sdhci-of-aspeed.c
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@ -59,6 +59,7 @@ struct aspeed_sdhci_phase_desc {
};
struct aspeed_sdhci_pdata {
unsigned int clk_div_start;
const struct aspeed_sdhci_phase_desc *phase_desc;
size_t nr_phase_descs;
};
@ -200,10 +201,13 @@ static void aspeed_sdhci_set_clock(struct sdhci_host *host, unsigned int clock)
{
struct sdhci_pltfm_host *pltfm_host;
unsigned long parent, bus;
struct aspeed_sdhci *sdhci;
int div;
u16 clk;
pltfm_host = sdhci_priv(host);
sdhci = sdhci_pltfm_priv(pltfm_host);
parent = clk_get_rate(pltfm_host->clk);
sdhci_writew(host, 0, SDHCI_CLOCK_CONTROL);
@ -214,7 +218,23 @@ static void aspeed_sdhci_set_clock(struct sdhci_host *host, unsigned int clock)
if (WARN_ON(clock > host->max_clk))
clock = host->max_clk;
for (div = 2; div < 256; div *= 2) {
/*
* Regarding the AST2600:
*
* If (EMMC12C[7:6], EMMC12C[15:8] == 0) then
* period of SDCLK = period of SDMCLK.
*
* If (EMMC12C[7:6], EMMC12C[15:8] != 0) then
* period of SDCLK = period of SDMCLK * 2 * (EMMC12C[7:6], EMMC[15:8])
*
* If you keep EMMC12C[7:6] = 0 and EMMC12C[15:8] as one-hot,
* 0x1/0x2/0x4/etc, you will find it is compatible to AST2400 or AST2500
*
* Keep the one-hot behaviour for backwards compatibility except for
* supporting the value 0 in (EMMC12C[7:6], EMMC12C[15:8]), and capture
* the 0-value capability in clk_div_start.
*/
for (div = sdhci->pdata->clk_div_start; div < 256; div *= 2) {
bus = parent / div;
if (bus <= clock)
break;
@ -316,6 +336,10 @@ static int aspeed_sdhci_probe(struct platform_device *pdev)
int ret;
aspeed_pdata = of_device_get_match_data(&pdev->dev);
if (!aspeed_pdata) {
dev_err(&pdev->dev, "Missing platform configuration data\n");
return -EINVAL;
}
host = sdhci_pltfm_init(pdev, &aspeed_sdhci_pdata, sizeof(*dev));
if (IS_ERR(host))
@ -334,7 +358,7 @@ static int aspeed_sdhci_probe(struct platform_device *pdev)
else if (slot >= 2)
return -EINVAL;
if (dev->pdata && slot < dev->pdata->nr_phase_descs) {
if (slot < dev->pdata->nr_phase_descs) {
dev->phase_desc = &dev->pdata->phase_desc[slot];
} else {
dev_info(&pdev->dev,
@ -396,6 +420,10 @@ static int aspeed_sdhci_remove(struct platform_device *pdev)
return 0;
}
static const struct aspeed_sdhci_pdata ast2400_sdhci_pdata = {
.clk_div_start = 2,
};
static const struct aspeed_sdhci_phase_desc ast2600_sdhci_phase[] = {
/* SDHCI/Slot 0 */
[0] = {
@ -426,13 +454,14 @@ static const struct aspeed_sdhci_phase_desc ast2600_sdhci_phase[] = {
};
static const struct aspeed_sdhci_pdata ast2600_sdhci_pdata = {
.clk_div_start = 1,
.phase_desc = ast2600_sdhci_phase,
.nr_phase_descs = ARRAY_SIZE(ast2600_sdhci_phase),
};
static const struct of_device_id aspeed_sdhci_of_match[] = {
{ .compatible = "aspeed,ast2400-sdhci", },
{ .compatible = "aspeed,ast2500-sdhci", },
{ .compatible = "aspeed,ast2400-sdhci", .data = &ast2400_sdhci_pdata, },
{ .compatible = "aspeed,ast2500-sdhci", .data = &ast2400_sdhci_pdata, },
{ .compatible = "aspeed,ast2600-sdhci", .data = &ast2600_sdhci_pdata, },
{ }
};