[PATCH v7 6/6] mmc: sh_mobile_sdhi: Add tuning support

From: Simon Horman <horms+renesas@verge.net.au>
To: Wolfram Sang <wsa+renesas@sang-engineering.com>,
	Ulf Hansson <ulf.hansson@linaro.org>
Cc: Magnus Damm <magnus.damm@gmail.com>,
	linux-mmc@vger.kernel.org, linux-renesas-soc@vger.kernel.org,
	Simon Horman <horms+renesas@verge.net.au>,
	Ai Kyuse <ai.kyuse.uw@renesas.com>
Subject: [PATCH v7 6/6] mmc: sh_mobile_sdhi: Add tuning support
Date: Tue, 13 Sep 2016 12:56:15 +0200	[thread overview]
Message-ID: <1473764175-24580-7-git-send-email-horms+renesas@verge.net.au> (raw)
In-Reply-To: <1473764175-24580-1-git-send-email-horms+renesas@verge.net.au>

Add tuning support for use with SDR104 mode
This includes adding support for the sampling clock controller (SCC).

Based on work by Ai Kyuse.

Cc: Ai Kyuse <ai.kyuse.uw@renesas.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
---
v6 [Simon Horman]
* Rebase to use host->taps

v5 [Simon Horman]
* As suggested by Ulf Hansson
  - Use more descriptive name for callback to check for SSC error
* Correct return statement in sh_mobile_sdhi_hw_reset
* Reinstate Gen3 tuning support

v4 [Simon Horman]
As suggested by Geert Uytterhoeven:
* guard SDR104 specific portion of probe with host->mmc->caps &
  MMC_CAP_UHS_SDR104
* As suggested by Wolfram Sang:
  - Pass priv to sd_scc_{read,write}32 to save host_to_priv access
    for each call
  - Use 0x0 instead of other representations of 0 in hex
  - Use CLK_CTL_SCLKEN
  - Do not add unused SH_MOBILE_SDHI_MAX_TAP
  - Use ternary operator in sh_mobile_sdhi_select_tuning
  - Do include as yet unsupported HS200 in error string
* Reintroduce retuning support: This was removed in v3.
* Revert to algorithm in v1 patchset, on further reading of the documentation
  it appears to be correct.

v3 [Simon Horman]
* As suggested by Kuninori Morimoto:
  - Do not add unused retuning callback to struct tmio_mmc_host
  - Change return type of prepare_tuning callback to void
  - Add tap_size parameter to select_tuning callback

v2 [Simon Horman]
* As suggested by Kuninori Morimoto
  - Use host->mmc->caps & MMC_CAP_UHS_SDR104 instead of
    pdata->flags & TMIO_MMC_HAS_UHS_SCC to avoid needing the
    MMC_CAP_UHS_SDR104 flag at all.
    N.B: Morimoto-san suggested using but this flag is not actually
    set there in by current probe come.
  - Simplify logic in sh_mobile_sdhi_inquiry_tuning
* As suggested by Wolfram Sang
  - Use clk_rate instead of clk for field in struct sh_mobile_sdhi_scc
  - Remove inquiry_tuning callback which is now unnecessary as calling
    of tuning is handled by the core
  - Removed unused sh_mobile_sdhi_set_clk_div callback
  - Save sci_base address rather than calculating it on each read and write
* Update selection logic in sh_mobile_sdhi_select_tuning to match spec
* Use bool instead of long for taps parameter of
  sh_mobile_sdhi_select_tuning()
* Return 0 from sh_mobile_sdhi_init_tuning() if the
  SDR104 capability is not set and thus tuning should not
  be performed because it is not supported by the hardware

v1 [Simon Horman]
* Rebase
* Always use value of 0x8 for TAPNUM field of DTCNTL register
  rather than reading value from DT property. There does not
  seem to be a need to expose this in DT at this point.
* Do not include tmio_mmc_start_signal_voltage_switch changes which
  are already in mainline in a different form
* Do not add renesas,clk-rate property as the max-frequency property, which
  is now present in mainline, seems to provide the needed rate
* Omit Gen3 specific changes
* Do not provide renesas,mmc-scc-tappos DT property.
  Instead, always use taps provided in driver.
* Do not parse sd-uhs-sdr50 and sd-uhs-sdr104 properties.
  This is handled by the core.

v0 [Ai Kyuse]

Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
---
 drivers/mmc/host/sh_mobile_sdhi.c | 265 +++++++++++++++++++++++++++++++++++++-
 1 file changed, 264 insertions(+), 1 deletion(-)

diff --git a/drivers/mmc/host/sh_mobile_sdhi.c b/drivers/mmc/host/sh_mobile_sdhi.c
index 49edff7fee49..32d3e01e0840 100644
--- a/drivers/mmc/host/sh_mobile_sdhi.c
+++ b/drivers/mmc/host/sh_mobile_sdhi.c
@@ -47,6 +47,11 @@
 
 #define host_to_priv(host) container_of((host)->pdata, struct sh_mobile_sdhi, mmc_data)
 
+struct sh_mobile_sdhi_scc {
+	unsigned long clk_rate;	/* clock rate for SDR104 */
+	u32 tap;		/* sampling clock position for SDR104 */
+};
+
 struct sh_mobile_sdhi_of_data {
 	unsigned long tmio_flags;
 	unsigned long capabilities;
@@ -54,6 +59,9 @@ struct sh_mobile_sdhi_of_data {
 	enum dma_slave_buswidth dma_buswidth;
 	dma_addr_t dma_rx_offset;
 	unsigned bus_shift;
+	int scc_offset;
+	struct sh_mobile_sdhi_scc *taps;
+	int taps_num;
 };
 
 static const struct sh_mobile_sdhi_of_data of_default_cfg = {
@@ -66,12 +74,35 @@ static const struct sh_mobile_sdhi_of_data of_rcar_gen1_compatible = {
 	.capabilities	= MMC_CAP_SD_HIGHSPEED | MMC_CAP_SDIO_IRQ,
 };
 
+/* Definitions for sampling clocks */
+static struct sh_mobile_sdhi_scc rcar_gen2_scc_taps[] = {
+	{
+		.clk_rate = 156000000,
+		.tap = 0x00000703,
+	},
+	{
+		.clk_rate = 0,
+		.tap = 0x00000300,
+	},
+};
+
 static const struct sh_mobile_sdhi_of_data of_rcar_gen2_compatible = {
 	.tmio_flags	= TMIO_MMC_HAS_IDLE_WAIT | TMIO_MMC_WRPROTECT_DISABLE |
 			  TMIO_MMC_CLK_ACTUAL | TMIO_MMC_MIN_RCAR2,
 	.capabilities	= MMC_CAP_SD_HIGHSPEED | MMC_CAP_SDIO_IRQ,
 	.dma_buswidth	= DMA_SLAVE_BUSWIDTH_4_BYTES,
 	.dma_rx_offset	= 0x2000,
+	.scc_offset	= 0x0300,
+	.taps		= rcar_gen2_scc_taps,
+	.taps_num	= ARRAY_SIZE(rcar_gen2_scc_taps),
+};
+
+/* Definitions for sampling clocks */
+static struct sh_mobile_sdhi_scc rcar_gen3_scc_taps[] = {
+	{
+		.clk_rate = 0,
+		.tap = 0x00000300,
+	},
 };
 
 static const struct sh_mobile_sdhi_of_data of_rcar_gen3_compatible = {
@@ -79,6 +110,9 @@ static const struct sh_mobile_sdhi_of_data of_rcar_gen3_compatible = {
 			  TMIO_MMC_CLK_ACTUAL | TMIO_MMC_MIN_RCAR2,
 	.capabilities	= MMC_CAP_SD_HIGHSPEED | MMC_CAP_SDIO_IRQ,
 	.bus_shift	= 2,
+	.scc_offset	= 0x1000,
+	.taps		= rcar_gen3_scc_taps,
+	.taps_num	= ARRAY_SIZE(rcar_gen3_scc_taps),
 };
 
 static const struct of_device_id sh_mobile_sdhi_of_match[] = {
@@ -105,6 +139,7 @@ struct sh_mobile_sdhi {
 	struct tmio_mmc_dma dma_priv;
 	struct pinctrl *pinctrl;
 	struct pinctrl_state *pins_default, *pins_uhs;
+	void __iomem *scc_ctl;
 };
 
 static void sh_mobile_sdhi_sdbuf_width(struct tmio_mmc_host *host, int width)
@@ -255,6 +290,201 @@ static int sh_mobile_sdhi_start_signal_voltage_switch(struct mmc_host *mmc,
 	return pinctrl_select_state(priv->pinctrl, pin_state);
 }
 
+/* SCC registers */
+#define SH_MOBILE_SDHI_SCC_DTCNTL	0x000
+#define SH_MOBILE_SDHI_SCC_TAPSET	0x002
+#define SH_MOBILE_SDHI_SCC_DT2FF	0x004
+#define SH_MOBILE_SDHI_SCC_CKSEL	0x006
+#define SH_MOBILE_SDHI_SCC_RVSCNTL	0x008
+#define SH_MOBILE_SDHI_SCC_RVSREQ	0x00A
+
+/* Definitions for values the SH_MOBILE_SDHI_SCC_DTCNTL register */
+#define SH_MOBILE_SDHI_SCC_DTCNTL_TAPEN		BIT(0)
+#define SH_MOBILE_SDHI_SCC_DTCNTL_TAPNUM_SHIFT	16
+#define SH_MOBILE_SDHI_SCC_DTCNTL_TAPNUM_MASK	0xff
+
+/* Definitions for values the SH_MOBILE_SDHI_SCC_CKSEL register */
+#define SH_MOBILE_SDHI_SCC_CKSEL_DTSEL		BIT(0)
+/* Definitions for values the SH_MOBILE_SDHI_SCC_RVSCNTL register */
+#define SH_MOBILE_SDHI_SCC_RVSCNTL_RVSEN	BIT(1)
+/* Definitions for values the SH_MOBILE_SDHI_SCC_RVSREQ register */
+#define SH_MOBILE_SDHI_SCC_RVSREQ_RVSERR	BIT(2)
+
+static inline u32 sd_scc_read32(struct tmio_mmc_host *host,
+				struct sh_mobile_sdhi *priv, int addr)
+{
+	return readl(priv->scc_ctl + (addr << host->bus_shift));
+}
+
+static inline void sd_scc_write32(struct tmio_mmc_host *host,
+				  struct sh_mobile_sdhi *priv,
+				  int addr, u32 val)
+{
+	writel(val, priv->scc_ctl + (addr << host->bus_shift));
+}
+
+static unsigned int sh_mobile_sdhi_init_tuning(struct tmio_mmc_host *host)
+{
+	struct sh_mobile_sdhi *priv;
+
+	if (!(host->mmc->caps & MMC_CAP_UHS_SDR104))
+		return 0;
+
+	priv = host_to_priv(host);
+
+	/* set sampling clock selection range */
+	sd_scc_write32(host, priv, SH_MOBILE_SDHI_SCC_DTCNTL,
+		       0x8 << SH_MOBILE_SDHI_SCC_DTCNTL_TAPNUM_SHIFT);
+
+	/* Initialize SCC */
+	sd_ctrl_write32_as_16_and_16(host, CTL_STATUS, 0x0);
+
+	sd_scc_write32(host, priv, SH_MOBILE_SDHI_SCC_DTCNTL,
+		       SH_MOBILE_SDHI_SCC_DTCNTL_TAPEN |
+		       sd_scc_read32(host, priv, SH_MOBILE_SDHI_SCC_DTCNTL));
+
+	sd_ctrl_write16(host, CTL_SD_CARD_CLK_CTL, ~CLK_CTL_SCLKEN &
+			sd_ctrl_read16(host, CTL_SD_CARD_CLK_CTL));
+
+	sd_scc_write32(host, priv, SH_MOBILE_SDHI_SCC_CKSEL,
+		       SH_MOBILE_SDHI_SCC_CKSEL_DTSEL |
+		       sd_scc_read32(host, priv, SH_MOBILE_SDHI_SCC_CKSEL));
+
+	sd_ctrl_write16(host, CTL_SD_CARD_CLK_CTL, CLK_CTL_SCLKEN |
+			sd_ctrl_read16(host, CTL_SD_CARD_CLK_CTL));
+
+	sd_scc_write32(host, priv, SH_MOBILE_SDHI_SCC_RVSCNTL,
+		       ~SH_MOBILE_SDHI_SCC_RVSCNTL_RVSEN &
+		       sd_scc_read32(host, priv, SH_MOBILE_SDHI_SCC_RVSCNTL));
+
+	sd_scc_write32(host, priv, SH_MOBILE_SDHI_SCC_DT2FF, host->scc_tappos);
+
+	/* Read TAPNUM */
+	return (sd_scc_read32(host, priv, SH_MOBILE_SDHI_SCC_DTCNTL) >>
+		SH_MOBILE_SDHI_SCC_DTCNTL_TAPNUM_SHIFT) &
+		SH_MOBILE_SDHI_SCC_DTCNTL_TAPNUM_MASK;
+}
+
+static void sh_mobile_sdhi_prepare_tuning(struct tmio_mmc_host *host,
+					 unsigned long tap)
+{
+	struct sh_mobile_sdhi *priv = host_to_priv(host);
+
+	/* Set sampling clock position */
+	sd_scc_write32(host, priv, SH_MOBILE_SDHI_SCC_TAPSET, tap);
+}
+
+#define SH_MOBILE_SDHI_MAX_TAP 3
+
+static int sh_mobile_sdhi_select_tuning(struct tmio_mmc_host *host)
+{
+	struct sh_mobile_sdhi *priv = host_to_priv(host);
+	unsigned long tap_cnt;  /* counter of tuning success */
+	unsigned long tap_set;  /* tap position */
+	unsigned long tap_start;/* start position of tuning success */
+	unsigned long tap_end;  /* end position of tuning success */
+	unsigned long ntap;     /* temporary counter of tuning success */
+	unsigned long i;
+
+	/* Clear SCC_RVSREQ */
+	sd_scc_write32(host, priv, SH_MOBILE_SDHI_SCC_RVSREQ, 0);
+
+	/*
+	 * Find the longest consecutive run of successful probes.  If that
+	 * is more than SH_MOBILE_SDHI_MAX_TAP probes long then use the
+	 * center index as the tap.
+	 */
+	tap_cnt = 0;
+	ntap = 0;
+	tap_start = 0;
+	tap_end = 0;
+	for (i = 0; i < host->tap_num * 2; i++) {
+		if (test_bit(i, host->taps))
+			ntap++;
+		else {
+			if (ntap > tap_cnt) {
+				tap_start = i - ntap;
+				tap_end = i - 1;
+				tap_cnt = ntap;
+			}
+			ntap = 0;
+		}
+	}
+
+	if (ntap > tap_cnt) {
+		tap_start = i - ntap;
+		tap_end = i - 1;
+		tap_cnt = ntap;
+	}
+
+	if (tap_cnt >= SH_MOBILE_SDHI_MAX_TAP)
+		tap_set = (tap_start + tap_end) / 2 % host->tap_num;
+	else
+		return -EIO;
+
+	/* Set SCC */
+	sd_scc_write32(host, priv, SH_MOBILE_SDHI_SCC_TAPSET, tap_set);
+
+	/* Enable auto re-tuning */
+	sd_scc_write32(host, priv, SH_MOBILE_SDHI_SCC_RVSCNTL,
+		       SH_MOBILE_SDHI_SCC_RVSCNTL_RVSEN |
+		       sd_scc_read32(host, priv, SH_MOBILE_SDHI_SCC_RVSCNTL));
+
+	return 0;
+}
+
+
+static bool sh_mobile_sdhi_check_scc_error(struct tmio_mmc_host *host)
+{
+	struct sh_mobile_sdhi *priv;
+
+	if (!(host->mmc->caps & MMC_CAP_UHS_SDR104))
+		return 0;
+
+	priv = host_to_priv(host);
+
+	/* Check SCC error */
+	if (sd_scc_read32(host, priv, SH_MOBILE_SDHI_SCC_RVSCNTL) &
+	    SH_MOBILE_SDHI_SCC_RVSCNTL_RVSEN &&
+	    sd_scc_read32(host, priv, SH_MOBILE_SDHI_SCC_RVSREQ) &
+	    SH_MOBILE_SDHI_SCC_RVSREQ_RVSERR) {
+		/* Clear SCC error */
+		sd_scc_write32(host, priv, SH_MOBILE_SDHI_SCC_RVSREQ, 0);
+		return true;
+	}
+
+	return false;
+}
+
+static void sh_mobile_sdhi_hw_reset(struct tmio_mmc_host *host)
+{
+	struct sh_mobile_sdhi *priv;
+
+	if (host->mmc->caps & MMC_CAP_UHS_SDR104)
+		return;
+
+	priv = host_to_priv(host);
+
+	/* Reset SCC */
+	sd_ctrl_write16(host, CTL_SD_CARD_CLK_CTL, ~CLK_CTL_SCLKEN &
+			sd_ctrl_read16(host, CTL_SD_CARD_CLK_CTL));
+
+	sd_scc_write32(host, priv, SH_MOBILE_SDHI_SCC_CKSEL,
+		       ~SH_MOBILE_SDHI_SCC_CKSEL_DTSEL &
+		       sd_scc_read32(host, priv, SH_MOBILE_SDHI_SCC_CKSEL));
+
+	sd_ctrl_write16(host, CTL_SD_CARD_CLK_CTL, CLK_CTL_SCLKEN |
+			sd_ctrl_read16(host, CTL_SD_CARD_CLK_CTL));
+
+	sd_scc_write32(host, priv, SH_MOBILE_SDHI_SCC_RVSCNTL,
+		       ~SH_MOBILE_SDHI_SCC_RVSCNTL_RVSEN &
+		       sd_scc_read32(host, priv, SH_MOBILE_SDHI_SCC_RVSCNTL));
+
+	sd_scc_write32(host, priv, SH_MOBILE_SDHI_SCC_RVSCNTL,
+		       ~SH_MOBILE_SDHI_SCC_RVSCNTL_RVSEN &
+		       sd_scc_read32(host, priv, SH_MOBILE_SDHI_SCC_RVSCNTL));
+}
+
 static int sh_mobile_sdhi_wait_idle(struct tmio_mmc_host *host)
 {
 	int timeout = 1000;
@@ -325,7 +555,7 @@ static int sh_mobile_sdhi_probe(struct platform_device *pdev)
 	struct tmio_mmc_data *mmd = pdev->dev.platform_data;
 	struct tmio_mmc_host *host;
 	struct resource *res;
-	int irq, ret, i = 0;
+	int irq, ret, i;
 	struct tmio_mmc_dma *dma_priv;
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
@@ -384,6 +614,11 @@ static int sh_mobile_sdhi_probe(struct platform_device *pdev)
 		host->card_busy	= sh_mobile_sdhi_card_busy;
 		host->start_signal_voltage_switch =
 			sh_mobile_sdhi_start_signal_voltage_switch;
+		host->init_tuning	= sh_mobile_sdhi_init_tuning;
+		host->prepare_tuning	= sh_mobile_sdhi_prepare_tuning;
+		host->select_tuning	= sh_mobile_sdhi_select_tuning;
+		host->check_scc_error	= sh_mobile_sdhi_check_scc_error;
+		host->hw_reset		= sh_mobile_sdhi_hw_reset;
 	}
 
 	/* Orginally registers were 16 bit apart, could be 32 or 64 nowadays */
@@ -424,6 +659,34 @@ static int sh_mobile_sdhi_probe(struct platform_device *pdev)
 	if (ret < 0)
 		goto efree;
 
+	if (host->mmc->caps & MMC_CAP_UHS_SDR104) {
+		host->mmc->caps |= MMC_CAP_HW_RESET;
+
+		if (of_id && of_id->data) {
+			const struct sh_mobile_sdhi_of_data *of_data;
+			const struct sh_mobile_sdhi_scc *taps;
+			bool hit = false;
+
+			of_data = of_id->data;
+			taps = of_data->taps;
+
+			for (i = 0; i < of_data->taps_num; i++) {
+				if (taps[i].clk_rate == 0 ||
+				    taps[i].clk_rate == host->mmc->f_max) {
+					host->scc_tappos = taps->tap;
+					hit = true;
+					break;
+				}
+			}
+
+			if (!hit)
+				dev_warn(&host->pdev->dev, "Unknown clock rate for SDR104\n");
+
+			priv->scc_ctl = host->ctl + of_data->scc_offset;
+		}
+	}
+
+	i = 0;
 	while (1) {
 		irq = platform_get_irq(pdev, i);
 		if (irq < 0)
-- 
2.7.0.rc3.207.g0ac5344
