@@ -119,7 +119,20 @@ static int sh_mobile_sdhi_clk_enable(struct tmio_mmc_host *host)
if (ret < 0)
return ret;
- mmc->f_max = clk_get_rate(priv->clk);
+ /*
+ * The clock driver may not know what maximum frequency
+ * actually works, so it should be set with the max-frequency
+ * property which will already have been read to f_max. If it
+ * was missing, assume the current frequency is the maximum.
+ */
+ if (!mmc->f_max)
+ mmc->f_max = clk_get_rate(priv->clk);
+
+ /*
+ * Minimum frequency is the minimum input clock frequency
+ * divided by our maximum divider.
+ */
+ mmc->f_min = max(clk_round_rate(priv->clk, 1) / 512, 1L);
/* enable 16bit data access on SDBUF as default */
sh_mobile_sdhi_sdbuf_width(host, 16);
@@ -127,6 +140,44 @@ static int sh_mobile_sdhi_clk_enable(struct tmio_mmc_host *host)
return 0;
}
+static unsigned int sh_mobile_sdhi_clk_update(struct tmio_mmc_host *host,
+ unsigned int new_clock)
+{
+ struct sh_mobile_sdhi *priv = host_to_priv(host);
+ unsigned int freq, best_freq, diff_min, diff;
+ int i;
+
+ diff_min = ~0;
+ best_freq = 0;
+
+ /*
+ * We want the bus clock to be as close as possible to, but no
+ * greater than, new_clock. As we can divide by 1 << i for
+ * any i in [0, 9] we want the input clock to be as close as
+ * possible, but no greater than, new_clock << i.
+ */
+ for (i = min(9, ilog2(UINT_MAX / new_clock)); i >= 0; i--) {
+ freq = clk_round_rate(priv->clk, new_clock << i);
+ if (freq > (new_clock << i)) {
+ /* Too fast; look for a slightly slower option */
+ freq = clk_round_rate(priv->clk,
+ (new_clock << i) / 4 * 3);
+ if (freq > (new_clock << i))
+ continue;
+ }
+
+ diff = new_clock - (freq >> i);
+ if (diff <= diff_min) {
+ best_freq = freq;
+ diff_min = diff;
+ }
+ }
+
+ clk_set_rate(priv->clk, best_freq);
+
+ return best_freq;
+}
+
static void sh_mobile_sdhi_clk_disable(struct tmio_mmc_host *host)
{
struct sh_mobile_sdhi *priv = host_to_priv(host);
@@ -235,6 +286,7 @@ static int sh_mobile_sdhi_probe(struct platform_device *pdev)
host->dma = dma_priv;
host->write16_hook = sh_mobile_sdhi_write16_hook;
host->clk_enable = sh_mobile_sdhi_clk_enable;
+ host->clk_update = sh_mobile_sdhi_clk_update;
host->clk_disable = sh_mobile_sdhi_clk_disable;
host->multi_io_quirk = sh_mobile_sdhi_multi_io_quirk;
/* SD control register space size is 0x100, 0x200 for bus_shift=1 */
@@ -342,7 +394,7 @@ static int sh_mobile_sdhi_probe(struct platform_device *pdev)
}
}
- dev_info(&pdev->dev, "%s base at 0x%08lx clock rate %u MHz\n",
+ dev_info(&pdev->dev, "%s base at 0x%08lx max clock rate %u MHz\n",
mmc_hostname(host->mmc), (unsigned long)
(platform_get_resource(pdev, IORESOURCE_MEM, 0)->start),
host->mmc->f_max / 1000000);
@@ -96,6 +96,8 @@ struct tmio_mmc_host {
int (*write16_hook)(struct tmio_mmc_host *host, int addr);
int (*clk_enable)(struct tmio_mmc_host *host);
+ unsigned int (*clk_update)(struct tmio_mmc_host *host,
+ unsigned int new_clock);
void (*clk_disable)(struct tmio_mmc_host *host);
int (*multi_io_quirk)(struct mmc_card *card,
unsigned int direction, int blk_size);
@@ -156,8 +156,12 @@ static void tmio_mmc_set_clock(struct tmio_mmc_host *host,
u32 clk = 0, clock;
if (new_clock) {
- for (clock = host->mmc->f_min, clk = 0x80000080;
- new_clock >= (clock<<1); clk >>= 1)
+ if (host->clk_update)
+ clock = host->clk_update(host, new_clock) / 512;
+ else
+ clock = host->mmc->f_min;
+
+ for (clk = 0x80000080; new_clock >= (clock << 1); clk >>= 1)
clock <<= 1;
/* 1/1 clock is option */
@@ -832,19 +836,12 @@ fail:
pm_runtime_put_autosuspend(mmc_dev(mmc));
}
-static int tmio_mmc_clk_update(struct tmio_mmc_host *host)
+static int tmio_mmc_clk_enable(struct tmio_mmc_host *host)
{
- struct mmc_host *mmc = host->mmc;
- int ret;
-
if (!host->clk_enable)
return -ENOTSUPP;
- ret = host->clk_enable(host);
- if (!ret)
- mmc->f_min = mmc->f_max / 512;
-
- return ret;
+ return host->clk_enable(host);
}
static void tmio_mmc_power_on(struct tmio_mmc_host *host, unsigned short vdd)
@@ -1130,7 +1127,7 @@ int tmio_mmc_host_probe(struct tmio_mmc_host *_host,
mmc->caps & MMC_CAP_NONREMOVABLE ||
mmc->slot.cd_irq >= 0);
- if (tmio_mmc_clk_update(_host) < 0) {
+ if (tmio_mmc_clk_enable(_host) < 0) {
mmc->f_max = pdata->hclk;
mmc->f_min = mmc->f_max / 512;
}
@@ -1258,7 +1255,7 @@ int tmio_mmc_host_runtime_resume(struct device *dev)
struct tmio_mmc_host *host = mmc_priv(mmc);
tmio_mmc_reset(host);
- tmio_mmc_clk_update(host);
+ tmio_mmc_clk_enable(host);
if (host->clk_cache) {
tmio_mmc_set_clock(host, host->clk_cache);
Currently tmio_mmc assumes that the input clock frequency is fixed and only its own clock divider can be changed. This is not true in the case of sh_mobile_sdhi; we can use the clock API to change it. In tmio_mmc: - Delegate setting of f_min from tmio to the clk_enable operation (if implemented), as it can be smaller than f_max / 512 - Add an optional clk_update operation called from tmio_mmc_set_clock() that updates the input clock frequency - Rename tmio_mmc_clk_update() to tmio_mmc_clk_enable(), to avoid confusion with the clk_update operation In sh_mobile_sdhi: - Make the setting of f_max conditional; it should be set through the max-frequency property in the device tree in future - Set f_min based on the input clock's minimum frequency - Implement the clk_update operation, selecting the best input clock frequency for the bus frequency that's wanted sh_mobile_sdhi_clk_update() is loosely based on Kuninori Morimoto's work in sh_mmcif. Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk> --- drivers/mmc/host/sh_mobile_sdhi.c | 56 +++++++++++++++++++++++++++++++++++++-- drivers/mmc/host/tmio_mmc.h | 2 ++ drivers/mmc/host/tmio_mmc_pio.c | 23 +++++++--------- 3 files changed, 66 insertions(+), 15 deletions(-)