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Subject[PATCH v2 04/16] mmc: sdhci-omap: Add tuning support
Date
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@ti.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.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 86b6cc0a5380..36e0626d3de2 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
@@ -63,12 +70,16 @@

#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
@@ -77,6 +88,8 @@
#define IOV_3V0 3000000 /* 300000 uV */
#define IOV_3V3 3300000 /* 330000 uV */

+#define MAX_PHASE_DELAY 0x7C
+
struct sdhci_omap_data {
u32 offset;
};
@@ -198,6 +211,120 @@ 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)
+{
+ 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;
+
+ pltfm_host = sdhci_priv(host);
+ omap_host = sdhci_pltfm_priv(pltfm_host);
+ dev = omap_host->dev;
+
+ /* 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)
{
u32 reg, ac12;
@@ -299,6 +426,8 @@ 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;
}

@@ -635,6 +764,7 @@ 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;
--
2.11.0
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