Commit 2fb55956 authored by Ben Hutchings's avatar Ben Hutchings Committed by Ulf Hansson
Browse files

mmc: tmio, sh_mobile_sdhi: Add support for variable input clock frequency 



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: default avatarBen Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: default avatarWolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: default avatarUlf Hansson <ulf.hansson@linaro.org>
parent 0ea28210

drivers/mmc/host/sh_mobile_sdhi.c

+54 −2
Original line number Diff line number Diff line
@@ -139,14 +139,65 @@ static int sh_mobile_sdhi_clk_enable(struct tmio_mmc_host *host) 
	if (ret < 0)

		return ret;



	/*

	 * 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);



	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);
@@ -265,6 +316,7 @@ 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;
@@ -362,7 +414,7 @@ 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);

drivers/mmc/host/tmio_mmc.h

+2 −0
Original line number Diff line number Diff line
@@ -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);

drivers/mmc/host/tmio_mmc_pio.c

+10 −14
Original line number Diff line number Diff line
@@ -160,9 +160,12 @@ 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 */
@@ -837,19 +840,12 @@ 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)
@@ -1135,7 +1131,7 @@ 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;

	}
@@ -1263,7 +1259,7 @@ 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);

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