Re: [PATCH v3 2/3] mmc: sdhci-of-at91: rework clocks management to support SAM9x60 device

From: Adrian Hunter
Date: Mon Oct 28 2019 - 07:31:12 EST

On 25/10/19 11:03 AM, Ludovic Desroches wrote:
> In the SAM9x60 SoC, there are only two clocks instead of three for the
> SDHCI device. The base clk is no longer provided, it is generated
> internally from the mult clk.
>
> The values of the base clk and mul in the capabilities registers may not
> reflect the reality as the mult clk is a programmable clock which can take
> several rates. As we can't trust those values, take them from the clock
> tree and update the capabilities according to.
>
> As we can have the same pitfall, in some cases, with the SAMA5D2 Soc,
> stop relying on capabilities too.
>
> Signed-off-by: Ludovic Desroches <ludovic.desroches@xxxxxxxxxxxxx>
> ---
>
> Changes:
> - v3: none
> - v2: none
>
> drivers/mmc/host/sdhci-of-at91.c | 105 +++++++++++++++++--------------
> 1 file changed, 58 insertions(+), 47 deletions(-)
>
> diff --git a/drivers/mmc/host/sdhci-of-at91.c b/drivers/mmc/host/sdhci-of-at91.c
> index 9571c4a882a9..7477471dac00 100644
> --- a/drivers/mmc/host/sdhci-of-at91.c
> +++ b/drivers/mmc/host/sdhci-of-at91.c
> @@ -33,7 +33,14 @@
>
> #define SDHCI_AT91_PRESET_COMMON_CONF 0x400 /* drv type B, programmable clock mode */
>
> +struct sdhci_at91_soc_data {
> + const struct sdhci_pltfm_data *pdata;
> + bool baseclk_is_generated_internally;
> + unsigned int divider_for_baseclk;
> +};
> +
> struct sdhci_at91_priv {
> + const struct sdhci_at91_soc_data *soc_data;
> struct clk *hclock;
> struct clk *gck;
> struct clk *mainck;
> @@ -141,12 +148,24 @@ static const struct sdhci_ops sdhci_at91_sama5d2_ops = {
> .set_power = sdhci_at91_set_power,
> };
>
> -static const struct sdhci_pltfm_data soc_data_sama5d2 = {
> +static const struct sdhci_pltfm_data sdhci_sama5d2_pdata = {
> .ops = &sdhci_at91_sama5d2_ops,
> };
>
> +static const struct sdhci_at91_soc_data soc_data_sama5d2 = {
> + .pdata = &sdhci_sama5d2_pdata,
> + .baseclk_is_generated_internally = false,
> +};
> +
> +static const struct sdhci_at91_soc_data soc_data_sam9x60 = {
> + .pdata = &sdhci_sama5d2_pdata,
> + .baseclk_is_generated_internally = true,
> + .divider_for_baseclk = 2,
> +};
> +
> static const struct of_device_id sdhci_at91_dt_match[] = {
> { .compatible = "atmel,sama5d2-sdhci", .data = &soc_data_sama5d2 },
> + { .compatible = "microchip,sam9x60-sdhci", .data = &soc_data_sam9x60 },
> {}
> };
> MODULE_DEVICE_TABLE(of, sdhci_at91_dt_match);
> @@ -156,50 +175,37 @@ static int sdhci_at91_set_clks_presets(struct device *dev)
> struct sdhci_host *host = dev_get_drvdata(dev);
> struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
> struct sdhci_at91_priv *priv = sdhci_pltfm_priv(pltfm_host);
> - int ret;
> unsigned int caps0, caps1;
> unsigned int clk_base, clk_mul;
> - unsigned int gck_rate, real_gck_rate;
> + unsigned int gck_rate, clk_base_rate;
> unsigned int preset_div;
>
> - /*
> - * The mult clock is provided by as a generated clock by the PMC
> - * controller. In order to set the rate of gck, we have to get the
> - * base clock rate and the clock mult from capabilities.
> - */
> clk_prepare_enable(priv->hclock);
> caps0 = readl(host->ioaddr + SDHCI_CAPABILITIES);
> caps1 = readl(host->ioaddr + SDHCI_CAPABILITIES_1);
> - clk_base = (caps0 & SDHCI_CLOCK_V3_BASE_MASK) >> SDHCI_CLOCK_BASE_SHIFT;
> - clk_mul = (caps1 & SDHCI_CLOCK_MUL_MASK) >> SDHCI_CLOCK_MUL_SHIFT;
> - gck_rate = clk_base * 1000000 * (clk_mul + 1);
> - ret = clk_set_rate(priv->gck, gck_rate);
> - if (ret < 0) {
> - dev_err(dev, "failed to set gck");
> - clk_disable_unprepare(priv->hclock);
> - return ret;
> - }
> - /*
> - * We need to check if we have the requested rate for gck because in
> - * some cases this rate could be not supported. If it happens, the rate
> - * is the closest one gck can provide. We have to update the value
> - * of clk mul.
> - */
> - real_gck_rate = clk_get_rate(priv->gck);
> - if (real_gck_rate != gck_rate) {
> - clk_mul = real_gck_rate / (clk_base * 1000000) - 1;
> - caps1 &= (~SDHCI_CLOCK_MUL_MASK);
> - caps1 |= ((clk_mul << SDHCI_CLOCK_MUL_SHIFT) &
> - SDHCI_CLOCK_MUL_MASK);
> - /* Set capabilities in r/w mode. */
> - writel(SDMMC_CACR_KEY | SDMMC_CACR_CAPWREN,
> - host->ioaddr + SDMMC_CACR);
> - writel(caps1, host->ioaddr + SDHCI_CAPABILITIES_1);
> - /* Set capabilities in ro mode. */
> - writel(0, host->ioaddr + SDMMC_CACR);
> - dev_info(dev, "update clk mul to %u as gck rate is %u Hz\n",
> - clk_mul, real_gck_rate);
> - }
> +
> + gck_rate = clk_get_rate(priv->gck);
> + if (priv->soc_data->baseclk_is_generated_internally)
> + clk_base_rate = gck_rate / priv->soc_data->divider_for_baseclk;
> + else
> + clk_base_rate = clk_get_rate(priv->mainck);
> +
> + clk_base = clk_base_rate / 1000000;
> + clk_mul = gck_rate / clk_base_rate - 1;
> +
> + caps0 &= (~SDHCI_CLOCK_V3_BASE_MASK);
> + caps0 |= ((clk_base << SDHCI_CLOCK_BASE_SHIFT) & SDHCI_CLOCK_V3_BASE_MASK);
> + caps1 &= (~SDHCI_CLOCK_MUL_MASK);
> + caps1 |= ((clk_mul << SDHCI_CLOCK_MUL_SHIFT) & SDHCI_CLOCK_MUL_MASK);
> + /* Set capabilities in r/w mode. */
> + writel(SDMMC_CACR_KEY | SDMMC_CACR_CAPWREN, host->ioaddr + SDMMC_CACR);
> + writel(caps0, host->ioaddr + SDHCI_CAPABILITIES_1);

Shouldn't that be:

writel(caps0, host->ioaddr + SDHCI_CAPABILITIES);

> + writel(caps1, host->ioaddr + SDHCI_CAPABILITIES_1);
> + /* Set capabilities in ro mode. */
> + writel(0, host->ioaddr + SDMMC_CACR);
> +
> + dev_info(dev, "update clk mul to %u as gck rate is %u Hz and clk base is %u Hz\n",
> + clk_mul, gck_rate, clk_base_rate);
>
> /*
> * We have to set preset values because it depends on the clk_mul
> @@ -207,19 +213,19 @@ static int sdhci_at91_set_clks_presets(struct device *dev)
> * maximum sd clock value is 120 MHz instead of 208 MHz. For that
> * reason, we need to use presets to support SDR104.
> */
> - preset_div = DIV_ROUND_UP(real_gck_rate, 24000000) - 1;
> + preset_div = DIV_ROUND_UP(gck_rate, 24000000) - 1;
> writew(SDHCI_AT91_PRESET_COMMON_CONF | preset_div,
> host->ioaddr + SDHCI_PRESET_FOR_SDR12);
> - preset_div = DIV_ROUND_UP(real_gck_rate, 50000000) - 1;
> + preset_div = DIV_ROUND_UP(gck_rate, 50000000) - 1;
> writew(SDHCI_AT91_PRESET_COMMON_CONF | preset_div,
> host->ioaddr + SDHCI_PRESET_FOR_SDR25);
> - preset_div = DIV_ROUND_UP(real_gck_rate, 100000000) - 1;
> + preset_div = DIV_ROUND_UP(gck_rate, 100000000) - 1;
> writew(SDHCI_AT91_PRESET_COMMON_CONF | preset_div,
> host->ioaddr + SDHCI_PRESET_FOR_SDR50);
> - preset_div = DIV_ROUND_UP(real_gck_rate, 120000000) - 1;
> + preset_div = DIV_ROUND_UP(gck_rate, 120000000) - 1;
> writew(SDHCI_AT91_PRESET_COMMON_CONF | preset_div,
> host->ioaddr + SDHCI_PRESET_FOR_SDR104);
> - preset_div = DIV_ROUND_UP(real_gck_rate, 50000000) - 1;
> + preset_div = DIV_ROUND_UP(gck_rate, 50000000) - 1;
> writew(SDHCI_AT91_PRESET_COMMON_CONF | preset_div,
> host->ioaddr + SDHCI_PRESET_FOR_DDR50);
>
> @@ -314,7 +320,7 @@ static const struct dev_pm_ops sdhci_at91_dev_pm_ops = {
> static int sdhci_at91_probe(struct platform_device *pdev)
> {
> const struct of_device_id *match;
> - const struct sdhci_pltfm_data *soc_data;
> + const struct sdhci_at91_soc_data *soc_data;
> struct sdhci_host *host;
> struct sdhci_pltfm_host *pltfm_host;
> struct sdhci_at91_priv *priv;
> @@ -325,17 +331,22 @@ static int sdhci_at91_probe(struct platform_device *pdev)
> return -EINVAL;
> soc_data = match->data;
>
> - host = sdhci_pltfm_init(pdev, soc_data, sizeof(*priv));
> + host = sdhci_pltfm_init(pdev, soc_data->pdata, sizeof(*priv));
> if (IS_ERR(host))
> return PTR_ERR(host);
>
> pltfm_host = sdhci_priv(host);
> priv = sdhci_pltfm_priv(pltfm_host);
> + priv->soc_data = soc_data;
>
> priv->mainck = devm_clk_get(&pdev->dev, "baseclk");
> if (IS_ERR(priv->mainck)) {
> - dev_err(&pdev->dev, "failed to get baseclk\n");
> - return PTR_ERR(priv->mainck);
> + if (soc_data->baseclk_is_generated_internally) {
> + priv->mainck = NULL;
> + } else {
> + dev_err(&pdev->dev, "failed to get baseclk\n");
> + return PTR_ERR(priv->mainck);
> + }
> }
>
> priv->hclock = devm_clk_get(&pdev->dev, "hclock");
>