mmc: dw_mmc: Add driver callbacks for data read timeout

Current dw_mci driver supports a TMOUT register which consists of a 24
bit field (TMOUT[31:8]) for the DATA_TIMEOUT. The maximum value of this
field is 0xFFFFFF, which with a 200MHz clock will give a full DRTO of:

0xFFFFFF / 200000000 => ~84 ms

However, the ARTPEC-8 SoC DWMMC IP version has a TMOUT register with an
extended DATA_TIMEOUT field, which supports longer timers for the DRTO.
In this version the DATA_TIMEOUT field is split into two, which with the
same 200MHz clock as above will allow a maximum timeout of:

((TMOUT[10:8] -1) * 0xFFFFFF + TMOUT[31:11] * 8) / 200000000 => ~587 ms

Add driver callbacks for implementation specific data timeout, and
implement callback functions for the ARTPEC-8 SoC.

Signed-off-by: Mårten Lindahl <marten.lindahl@axis.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Link: https://lore.kernel.org/r/20211220113026.21129-4-marten.lindahl@axis.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/dw_mmc-exynos.c

@@ -539,6 +539,53 @@ static int dw_mci_exynos_prepare_hs400_tuning(struct dw_mci *host,
 	return 0;
 }
 
+static void dw_mci_exynos_set_data_timeout(struct dw_mci *host,
+					   unsigned int timeout_ns)
+{
+	u32 clk_div, tmout;
+	u64 tmp;
+	unsigned int tmp2;
+
+	clk_div = (mci_readl(host, CLKDIV) & 0xFF) * 2;
+	if (clk_div == 0)
+		clk_div = 1;
+
+	tmp = DIV_ROUND_UP_ULL((u64)timeout_ns * host->bus_hz, NSEC_PER_SEC);
+	tmp = DIV_ROUND_UP_ULL(tmp, clk_div);
+
+	/* TMOUT[7:0] (RESPONSE_TIMEOUT) */
+	tmout = 0xFF; /* Set maximum */
+
+	/*
+	 * Extended HW timer (max = 0x6FFFFF2):
+	 * ((TMOUT[10:8] - 1) * 0xFFFFFF + TMOUT[31:11] * 8)
+	 */
+	if (!tmp || tmp > 0x6FFFFF2)
+		tmout |= (0xFFFFFF << 8);
+	else {
+		/* TMOUT[10:8] */
+		tmp2 = (((unsigned int)tmp / 0xFFFFFF) + 1) & 0x7;
+		tmout |= tmp2 << 8;
+
+		/* TMOUT[31:11] */
+		tmp = tmp - ((tmp2 - 1) * 0xFFFFFF);
+		tmout |= (tmp & 0xFFFFF8) << 8;
+	}
+
+	mci_writel(host, TMOUT, tmout);
+	dev_dbg(host->dev, "timeout_ns: %u => TMOUT[31:8]: %#08x",
+		timeout_ns, tmout >> 8);
+}
+
+static u32 dw_mci_exynos_get_drto_clks(struct dw_mci *host)
+{
+	u32 drto_clks;
+
+	drto_clks = mci_readl(host, TMOUT) >> 8;
+
+	return (((drto_clks & 0x7) - 1) * 0xFFFFFF) + ((drto_clks & 0xFFFFF8));
+}
+
 /* Common capabilities of Exynos4/Exynos5 SoC */
 static unsigned long exynos_dwmmc_caps[4] = {
 	MMC_CAP_1_8V_DDR | MMC_CAP_8_BIT_DATA,
@@ -564,6 +611,8 @@ static const struct dw_mci_drv_data artpec_drv_data = {
 	.set_ios		= dw_mci_exynos_set_ios,
 	.parse_dt		= dw_mci_exynos_parse_dt,
 	.execute_tuning		= dw_mci_exynos_execute_tuning,
+	.set_data_timeout		= dw_mci_exynos_set_data_timeout,
+	.get_drto_clks		= dw_mci_exynos_get_drto_clks,
 };
 
 static const struct of_device_id dw_mci_exynos_match[] = {

drivers/mmc/host/dw_mmc.c

@@ -1287,9 +1287,13 @@ static void dw_mci_setup_bus(struct dw_mci_slot *slot, bool force_clkinit)
 static void dw_mci_set_data_timeout(struct dw_mci *host,
 				    unsigned int timeout_ns)
 {
+	const struct dw_mci_drv_data *drv_data = host->drv_data;
 	u32 clk_div, tmout;
 	u64 tmp;
 
+	if (drv_data && drv_data->set_data_timeout)
+		return drv_data->set_data_timeout(host, timeout_ns);
+
 	clk_div = (mci_readl(host, CLKDIV) & 0xFF) * 2;
 	if (clk_div == 0)
 		clk_div = 1;
@@ -1995,12 +1999,16 @@ static int dw_mci_data_complete(struct dw_mci *host, struct mmc_data *data)
 
 static void dw_mci_set_drto(struct dw_mci *host)
 {
+	const struct dw_mci_drv_data *drv_data = host->drv_data;
 	unsigned int drto_clks;
 	unsigned int drto_div;
 	unsigned int drto_ms;
 	unsigned long irqflags;
 
-	drto_clks = mci_readl(host, TMOUT) >> 8;
+	if (drv_data && drv_data->get_drto_clks)
+		drto_clks = drv_data->get_drto_clks(host);
+	else
+		drto_clks = mci_readl(host, TMOUT) >> 8;
 	drto_div = (mci_readl(host, CLKDIV) & 0xff) * 2;
 	if (drto_div == 0)
 		drto_div = 1;
@@ -2008,6 +2016,8 @@ static void dw_mci_set_drto(struct dw_mci *host)
 	drto_ms = DIV_ROUND_UP_ULL((u64)MSEC_PER_SEC * drto_clks * drto_div,
 				   host->bus_hz);
 
+	dev_dbg(host->dev, "drto_ms: %u\n", drto_ms);
+
 	/* add a bit spare time */
 	drto_ms += 10;
 

drivers/mmc/host/dw_mmc.h

@@ -556,6 +556,8 @@ struct dw_mci_slot {
  * @set_ios: handle bus specific extensions.
  * @parse_dt: parse implementation specific device tree properties.
  * @execute_tuning: implementation specific tuning procedure.
+ * @set_data_timeout: implementation specific timeout.
+ * @get_drto_clks: implementation specific cycle count for data read timeout.
  *
  * Provide controller implementation specific extensions. The usage of this
  * data structure is fully optional and usage of each member in this structure
@@ -573,5 +575,8 @@ struct dw_mci_drv_data {
 						struct mmc_ios *ios);
 	int		(*switch_voltage)(struct mmc_host *mmc,
 					  struct mmc_ios *ios);
+	void		(*set_data_timeout)(struct dw_mci *host,
+					  unsigned int timeout_ns);
+	u32		(*get_drto_clks)(struct dw_mci *host);
 };
 #endif /* _DW_MMC_H_ */