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mmc: sdhci-of-aspeed: Allow max-frequency limitation of SDCLK 

Add a get_max_clock() handler to sdhci-of-aspeed to report f_max as the
maximum clock rate if it is set. This enables artificial limitation of
the bus speed via max-frequency in the devicetree for e.g. the AST2600
evaluation board where I was seeing errors at 200MHz.

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
This commit is contained in:
Andrew Jeffery 2019-09-02 13:28:42 +09:30 committed by Ulf Hansson
parent 7b954cdf33
commit 0a0e8d7501
1 changed files with 18 additions and 2 deletions
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20
drivers/mmc/host/sdhci-of-aspeed.c
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@ -52,16 +52,24 @@ static void aspeed_sdc_configure_8bit_mode(struct aspeed_sdc *sdc,
static void aspeed_sdhci_set_clock(struct sdhci_host *host, unsigned int clock)
{
struct sdhci_pltfm_host *pltfm_host;
unsigned long parent;
int div;
u16 clk;
pltfm_host = sdhci_priv(host);
parent = clk_get_rate(pltfm_host->clk);
sdhci_writew(host, 0, SDHCI_CLOCK_CONTROL);
if (clock == 0)
return;
if (WARN_ON(clock > host->max_clk))
clock = host->max_clk;
for (div = 1; div < 256; div *= 2) {
if ((host->max_clk / div) <= clock)
if ((parent / div) <= clock)
break;
}
div >>= 1;
@ -71,6 +79,14 @@ static void aspeed_sdhci_set_clock(struct sdhci_host *host, unsigned int clock)
sdhci_enable_clk(host, clk);
}
static unsigned int aspeed_sdhci_get_max_clock(struct sdhci_host *host)
{
if (host->mmc->f_max)
return host->mmc->f_max;
return sdhci_pltfm_clk_get_max_clock(host);
}
static void aspeed_sdhci_set_bus_width(struct sdhci_host *host, int width)
{
struct sdhci_pltfm_host *pltfm_priv;
@ -97,7 +113,7 @@ static void aspeed_sdhci_set_bus_width(struct sdhci_host *host, int width)
static const struct sdhci_ops aspeed_sdhci_ops = {
.set_clock = aspeed_sdhci_set_clock,
.get_max_clock = sdhci_pltfm_clk_get_max_clock,
.get_max_clock = aspeed_sdhci_get_max_clock,
.set_bus_width = aspeed_sdhci_set_bus_width,
.get_timeout_clock = sdhci_pltfm_clk_get_max_clock,
.reset = sdhci_reset,