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Date: Thu, 21 Dec 2017 11:09:00 +0200
From: Adrian Hunter <adrian.hunter@...el.com>
To: Kishon Vijay Abraham I <kishon@...com>,
Ulf Hansson <ulf.hansson@...aro.org>,
Rob Herring <robh+dt@...nel.org>,
Tony Lindgren <tony@...mide.com>
Cc: Mark Rutland <mark.rutland@....com>,
Russell King <linux@...linux.org.uk>,
linux-mmc@...r.kernel.org, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-omap@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, nsekhar@...com
Subject: Re: [PATCH 04/12] mmc: sdhci-omap: Add tuning support
On 14/12/17 15:09, Kishon Vijay Abraham I wrote:
> MMC tuning procedure is required to support SD card
> UHS1-SDR104 mode and EMMC HS200 mode.
>
> SDR104/HS200 DLL Tuning Procedure for AM572x platform is mentioned
> in Figure 25-51. SDR104/HS200 DLL Tuning Procedure of
> AM572x Sitara Processors Silicon Revision 2.0, 1.1 TRM
> (SPRUHZ6I - October 2014–Revised April 2017 [1]).
>
> The tuning function sdhci_omap_execute_tuning() will only be
> called by the MMC/SD core if the corresponding speed modes
> are supported by the OMAP silicon which is set in the mmc
> host "caps" field.
>
> [1] -> http://www.ti.com/lit/ug/spruhz6i/spruhz6i.pdf
>
> Signed-off-by: Kishon Vijay Abraham I <kishon@...com>
Apart from 1 minor comment below:
Acked-by: Adrian Hunter <adrian.hunter@...el.com>
> ---
> drivers/mmc/host/sdhci-omap.c | 130 ++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 130 insertions(+)
>
> diff --git a/drivers/mmc/host/sdhci-omap.c b/drivers/mmc/host/sdhci-omap.c
> index 8f7239e2edc2..df8a0a472996 100644
> --- a/drivers/mmc/host/sdhci-omap.c
> +++ b/drivers/mmc/host/sdhci-omap.c
> @@ -37,6 +37,13 @@
> #define CON_INIT BIT(1)
> #define CON_OD BIT(0)
>
> +#define SDHCI_OMAP_DLL 0x0134
> +#define DLL_SWT BIT(20)
> +#define DLL_FORCE_SR_C_SHIFT 13
> +#define DLL_FORCE_SR_C_MASK (0x7f << DLL_FORCE_SR_C_SHIFT)
> +#define DLL_FORCE_VALUE BIT(12)
> +#define DLL_CALIB BIT(1)
> +
> #define SDHCI_OMAP_CMD 0x20c
>
> #define SDHCI_OMAP_PSTATE 0x0224
> @@ -66,12 +73,16 @@
>
> #define SDHCI_OMAP_AC12 0x23c
> #define AC12_V1V8_SIGEN BIT(19)
> +#define AC12_SCLK_SEL BIT(23)
>
> #define SDHCI_OMAP_CAPA 0x240
> #define CAPA_VS33 BIT(24)
> #define CAPA_VS30 BIT(25)
> #define CAPA_VS18 BIT(26)
>
> +#define SDHCI_OMAP_CAPA2 0x0244
> +#define CAPA2_TSDR50 BIT(13)
> +
> #define SDHCI_OMAP_TIMEOUT 1 /* 1 msec */
>
> #define SYSCTL_CLKD_MAX 0x3FF
> @@ -80,6 +91,8 @@
> #define IOV_3V0 3000000 /* 300000 uV */
> #define IOV_3V3 3300000 /* 330000 uV */
>
> +#define MAX_PHASE_DELAY 0x7C
> +
> struct sdhci_omap_data {
> u32 offset;
> };
> @@ -204,6 +217,120 @@ static void sdhci_omap_conf_bus_power(struct sdhci_omap_host *omap_host,
> }
> }
>
> +static inline void sdhci_omap_set_dll(struct sdhci_omap_host *omap_host,
> + int count)
> +{
> + int i;
> + u32 reg;
> +
> + reg = sdhci_omap_readl(omap_host, SDHCI_OMAP_DLL);
> + reg |= DLL_FORCE_VALUE;
> + reg &= ~DLL_FORCE_SR_C_MASK;
> + reg |= (count << DLL_FORCE_SR_C_SHIFT);
> + sdhci_omap_writel(omap_host, SDHCI_OMAP_DLL, reg);
> +
> + reg |= DLL_CALIB;
> + sdhci_omap_writel(omap_host, SDHCI_OMAP_DLL, reg);
> + for (i = 0; i < 1000; i++) {
> + reg = sdhci_omap_readl(omap_host, SDHCI_OMAP_DLL);
> + if (reg & DLL_CALIB)
> + break;
> + }
> + reg &= ~DLL_CALIB;
> + sdhci_omap_writel(omap_host, SDHCI_OMAP_DLL, reg);
> +}
> +
> +static void sdhci_omap_disable_tuning(struct sdhci_omap_host *omap_host)
> +{
> + u32 reg;
> +
> + reg = sdhci_omap_readl(omap_host, SDHCI_OMAP_AC12);
> + reg &= ~AC12_SCLK_SEL;
> + sdhci_omap_writel(omap_host, SDHCI_OMAP_AC12, reg);
> +
> + reg = sdhci_omap_readl(omap_host, SDHCI_OMAP_DLL);
> + reg &= ~(DLL_FORCE_VALUE | DLL_SWT);
> + sdhci_omap_writel(omap_host, SDHCI_OMAP_DLL, reg);
> +}
> +
> +static int sdhci_omap_execute_tuning(struct mmc_host *mmc, u32 opcode)
> +{
> + u32 reg;
> + int ret = 0;
> + u8 cur_match, prev_match = 0;
> + u32 phase_delay = 0;
> + u32 start_window = 0, max_window = 0;
> + u32 length = 0, max_len = 0;
> + struct mmc_ios *ios = &mmc->ios;
> + struct sdhci_host *host = mmc_priv(mmc);
> + struct sdhci_pltfm_host *pltfm_host;
> + struct sdhci_omap_host *omap_host;
> + struct device *dev;
> +
> + pltfm_host = sdhci_priv(host);
> + omap_host = sdhci_pltfm_priv(pltfm_host);
> + dev = omap_host->dev;
These initializations can be combined with the declarations. Also try to
arrange local variable declaration lines in descending order of length e.g.
struct sdhci_host *host = mmc_priv(mmc);
struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
struct sdhci_omap_host *omap_host = sdhci_pltfm_priv(pltfm_host);
struct device *dev = omap_host->dev;
struct mmc_ios *ios = &mmc->ios;
u32 start_window = 0, max_window = 0;
u8 cur_match, prev_match = 0;
u32 length = 0, max_len = 0;
u32 phase_delay = 0;
int ret = 0;
u32 reg;
> +
> + /* clock tuning is not needed for upto 52MHz */
> + if (ios->clock <= 52000000)
> + return 0;
> +
> + reg = sdhci_omap_readl(omap_host, SDHCI_OMAP_CAPA2);
> + if (ios->timing == MMC_TIMING_UHS_SDR50 && !(reg & CAPA2_TSDR50))
> + return 0;
> +
> + reg = sdhci_omap_readl(omap_host, SDHCI_OMAP_DLL);
> + reg |= DLL_SWT;
> + sdhci_omap_writel(omap_host, SDHCI_OMAP_DLL, reg);
> +
> + while (phase_delay <= MAX_PHASE_DELAY) {
> + sdhci_omap_set_dll(omap_host, phase_delay);
> +
> + cur_match = !mmc_send_tuning(mmc, opcode, NULL);
> + if (cur_match) {
> + if (prev_match) {
> + length++;
> + } else {
> + start_window = phase_delay;
> + length = 1;
> + }
> + }
> +
> + if (length > max_len) {
> + max_window = start_window;
> + max_len = length;
> + }
> +
> + prev_match = cur_match;
> + phase_delay += 4;
> + }
> +
> + if (!max_len) {
> + dev_err(dev, "Unable to find match\n");
> + ret = -EIO;
> + goto tuning_error;
> + }
> +
> + reg = sdhci_omap_readl(omap_host, SDHCI_OMAP_AC12);
> + if (!(reg & AC12_SCLK_SEL)) {
> + ret = -EIO;
> + goto tuning_error;
> + }
> +
> + phase_delay = max_window + 4 * (max_len >> 1);
> + sdhci_omap_set_dll(omap_host, phase_delay);
> +
> + goto ret;
> +
> +tuning_error:
> + dev_err(dev, "Tuning failed\n");
> + sdhci_omap_disable_tuning(omap_host);
> +
> +ret:
> + sdhci_reset(host, SDHCI_RESET_CMD | SDHCI_RESET_DATA);
> + return ret;
> +}
> +
> static int sdhci_omap_card_busy(struct mmc_host *mmc)
> {
> int i;
> @@ -312,6 +439,8 @@ static int sdhci_omap_start_signal_voltage_switch(struct mmc_host *mmc,
> static void sdhci_omap_set_power_mode(struct sdhci_omap_host *omap_host,
> u8 power_mode)
> {
> + if (omap_host->bus_mode == MMC_POWER_OFF)
> + sdhci_omap_disable_tuning(omap_host);
> omap_host->power_mode = power_mode;
> }
>
> @@ -648,6 +777,7 @@ static int sdhci_omap_probe(struct platform_device *pdev)
> sdhci_omap_start_signal_voltage_switch;
> host->mmc_host_ops.set_ios = sdhci_omap_set_ios;
> host->mmc_host_ops.card_busy = sdhci_omap_card_busy;
> + host->mmc_host_ops.execute_tuning = sdhci_omap_execute_tuning;
>
> sdhci_read_caps(host);
> host->caps |= SDHCI_CAN_DO_ADMA2;
>
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