Date:   Thu, 8 Dec 2016 13:53:10 +0200
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Masahiro Yamada <yamada.masahiro@...ionext.com>,
        linux-mmc@...r.kernel.org
Cc:     Ulf Hansson <ulf.hansson@...aro.org>,
        Douglas Anderson <dianders@...omium.org>,
        devicetree@...r.kernel.org, Al Cooper <alcooperx@...il.com>,
        linux-kernel@...r.kernel.org,
        Stefan Wahren <stefan.wahren@...e.com>,
        Rob Herring <robh+dt@...nel.org>,
        Andrei Pistirica <andrei.pistirica@...rochip.com>,
        Wolfram Sang <wsa+renesas@...g-engineering.com>,
        Joshua Henderson <joshua.henderson@...rochip.com>,
        Mark Rutland <mark.rutland@....com>,
        Simon Horman <horms+renesas@...ge.net.au>,
        Eric Anholt <eric@...olt.net>
Subject: Re: [PATCH v4 2/2] mmc: sdhci-cadence: add Cadence SD4HC support

On 05/12/16 04:10, Masahiro Yamada wrote:
> Add a driver for the Cadence SD4HC SD/SDIO/eMMC Controller.
> 
> For SD, it basically relies on the SDHCI standard code.
> For eMMC, this driver provides some callbacks to support the
> hardware part that is specific to this IP design.
> 
> Signed-off-by: Masahiro Yamada <yamada.masahiro@...ionext.com>

Acked-by: Adrian Hunter <adrian.hunter@...el.com>

> ---
> 
> Changes in v4:
>   - Override mmc_host_ops.execute_tuning instead of the
>     .platform_execute_tuning implementation
> 
> Changes in v3:
>   - Remove unneeded explanation about HRS and SRS from DT binding;
>     the offsets to HRS/SRS are fixed for this hardware and this is
>     quite normal, like each hardware has a fixed register view except
>     the register base.  The detailed register map is what the driver
>     cares about, so no need to explain it in the binding.
> 
> Changes in v2:
>   - Remove unnecessary "select MMC_SDHCI_IO_ACCESSORS"
> 
>  .../devicetree/bindings/mmc/sdhci-cadence.txt      |  30 +++
>  drivers/mmc/host/Kconfig                           |  11 +
>  drivers/mmc/host/Makefile                          |   1 +
>  drivers/mmc/host/sdhci-cadence.c                   | 280 +++++++++++++++++++++
>  4 files changed, 322 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/mmc/sdhci-cadence.txt
>  create mode 100644 drivers/mmc/host/sdhci-cadence.c
> 
> diff --git a/Documentation/devicetree/bindings/mmc/sdhci-cadence.txt b/Documentation/devicetree/bindings/mmc/sdhci-cadence.txt
> new file mode 100644
> index 0000000..750374f
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/mmc/sdhci-cadence.txt
> @@ -0,0 +1,30 @@
> +* Cadence SD/SDIO/eMMC Host Controller
> +
> +Required properties:
> +- compatible: should be "cdns,sd4hc".
> +- reg: offset and length of the register set for the device.
> +- interrupts: a single interrupt specifier.
> +- clocks: phandle to the input clock.
> +
> +Optional properties:
> +For eMMC configuration, supported speed modes are not indicated by the SDHCI
> +Capabilities Register.  Instead, the following properties should be specified
> +if supported.  See mmc.txt for details.
> +- mmc-ddr-1_8v
> +- mmc-ddr-1_2v
> +- mmc-hs200-1_8v
> +- mmc-hs200-1_2v
> +- mmc-hs400-1_8v
> +- mmc-hs400-1_2v
> +
> +Example:
> +	emmc: sdhci@...00000 {
> +		compatible = "cdns,sd4hc";
> +		reg = <0x5a000000 0x400>;
> +		interrupts = <0 78 4>;
> +		clocks = <&clk 4>;
> +		bus-width = <8>;
> +		mmc-ddr-1_8v;
> +		mmc-hs200-1_8v;
> +		mmc-hs400-1_8v;
> +	};
> diff --git a/drivers/mmc/host/Kconfig b/drivers/mmc/host/Kconfig
> index ab9181e..8ac1640 100644
> --- a/drivers/mmc/host/Kconfig
> +++ b/drivers/mmc/host/Kconfig
> @@ -164,6 +164,17 @@ config MMC_SDHCI_OF_HLWD
>  
>  	  If unsure, say N.
>  
> +config MMC_SDHCI_CADENCE
> +	tristate "SDHCI support for the Cadence SD/SDIO/eMMC controller"
> +	depends on MMC_SDHCI_PLTFM
> +	depends on OF
> +	help
> +	  This selects the Cadence SD/SDIO/eMMC driver.
> +
> +	  If you have a controller with this interface, say Y or M here.
> +
> +	  If unsure, say N.
> +
>  config MMC_SDHCI_CNS3XXX
>  	tristate "SDHCI support on the Cavium Networks CNS3xxx SoC"
>  	depends on ARCH_CNS3XXX
> diff --git a/drivers/mmc/host/Makefile b/drivers/mmc/host/Makefile
> index e49a82a..55f7193 100644
> --- a/drivers/mmc/host/Makefile
> +++ b/drivers/mmc/host/Makefile
> @@ -63,6 +63,7 @@ obj-$(CONFIG_MMC_REALTEK_PCI)	+= rtsx_pci_sdmmc.o
>  obj-$(CONFIG_MMC_REALTEK_USB)	+= rtsx_usb_sdmmc.o
>  
>  obj-$(CONFIG_MMC_SDHCI_PLTFM)		+= sdhci-pltfm.o
> +obj-$(CONFIG_MMC_SDHCI_CADENCE)		+= sdhci-cadence.o
>  obj-$(CONFIG_MMC_SDHCI_CNS3XXX)		+= sdhci-cns3xxx.o
>  obj-$(CONFIG_MMC_SDHCI_ESDHC_IMX)	+= sdhci-esdhc-imx.o
>  obj-$(CONFIG_MMC_SDHCI_DOVE)		+= sdhci-dove.o
> diff --git a/drivers/mmc/host/sdhci-cadence.c b/drivers/mmc/host/sdhci-cadence.c
> new file mode 100644
> index 0000000..6e2545f
> --- /dev/null
> +++ b/drivers/mmc/host/sdhci-cadence.c
> @@ -0,0 +1,280 @@
> +/*
> + * Copyright (C) 2016 Socionext Inc.
> + *   Author: Masahiro Yamada <yamada.masahiro@...ionext.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +
> +#include <linux/bitops.h>
> +#include <linux/iopoll.h>
> +#include <linux/module.h>
> +#include <linux/mmc/host.h>
> +
> +#include "sdhci-pltfm.h"
> +
> +/* HRS - Host Register Set (specific to Cadence) */
> +#define SDHCI_CDNS_HRS04		0x10		/* PHY access port */
> +#define   SDHCI_CDNS_HRS04_ACK			BIT(26)
> +#define   SDHCI_CDNS_HRS04_RD			BIT(25)
> +#define   SDHCI_CDNS_HRS04_WR			BIT(24)
> +#define   SDHCI_CDNS_HRS04_RDATA_SHIFT		12
> +#define   SDHCI_CDNS_HRS04_WDATA_SHIFT		8
> +#define   SDHCI_CDNS_HRS04_ADDR_SHIFT		0
> +
> +#define SDHCI_CDNS_HRS06		0x18		/* eMMC control */
> +#define   SDHCI_CDNS_HRS06_TUNE_UP		BIT(15)
> +#define   SDHCI_CDNS_HRS06_TUNE_SHIFT		8
> +#define   SDHCI_CDNS_HRS06_TUNE_MASK		0x3f
> +#define   SDHCI_CDNS_HRS06_MODE_MASK		0x7
> +#define   SDHCI_CDNS_HRS06_MODE_SD		0x0
> +#define   SDHCI_CDNS_HRS06_MODE_MMC_SDR		0x2
> +#define   SDHCI_CDNS_HRS06_MODE_MMC_DDR		0x3
> +#define   SDHCI_CDNS_HRS06_MODE_MMC_HS200	0x4
> +#define   SDHCI_CDNS_HRS06_MODE_MMC_HS400	0x5
> +
> +/* SRS - Slot Register Set (SDHCI-compatible) */
> +#define SDHCI_CDNS_SRS_BASE		0x200
> +
> +/* PHY */
> +#define SDHCI_CDNS_PHY_DLY_SD_HS	0x00
> +#define SDHCI_CDNS_PHY_DLY_SD_DEFAULT	0x01
> +#define SDHCI_CDNS_PHY_DLY_UHS_SDR12	0x02
> +#define SDHCI_CDNS_PHY_DLY_UHS_SDR25	0x03
> +#define SDHCI_CDNS_PHY_DLY_UHS_SDR50	0x04
> +#define SDHCI_CDNS_PHY_DLY_UHS_DDR50	0x05
> +#define SDHCI_CDNS_PHY_DLY_EMMC_LEGACY	0x06
> +#define SDHCI_CDNS_PHY_DLY_EMMC_SDR	0x07
> +#define SDHCI_CDNS_PHY_DLY_EMMC_DDR	0x08
> +
> +/*
> + * The tuned val register is 6 bit-wide, but not the whole of the range is
> + * available.  The range 0-42 seems to be available (then 43 wraps around to 0)
> + * but I am not quite sure if it is official.  Use only 0 to 39 for safety.
> + */
> +#define SDHCI_CDNS_MAX_TUNING_LOOP	40
> +
> +struct sdhci_cdns_priv {
> +	void __iomem *hrs_addr;
> +};
> +
> +static void sdhci_cdns_write_phy_reg(struct sdhci_cdns_priv *priv,
> +				     u8 addr, u8 data)
> +{
> +	void __iomem *reg = priv->hrs_addr + SDHCI_CDNS_HRS04;
> +	u32 tmp;
> +
> +	tmp = (data << SDHCI_CDNS_HRS04_WDATA_SHIFT) |
> +	      (addr << SDHCI_CDNS_HRS04_ADDR_SHIFT);
> +	writel(tmp, reg);
> +
> +	tmp |= SDHCI_CDNS_HRS04_WR;
> +	writel(tmp, reg);
> +
> +	tmp &= ~SDHCI_CDNS_HRS04_WR;
> +	writel(tmp, reg);
> +}
> +
> +static void sdhci_cdns_phy_init(struct sdhci_cdns_priv *priv)
> +{
> +	sdhci_cdns_write_phy_reg(priv, SDHCI_CDNS_PHY_DLY_SD_HS, 4);
> +	sdhci_cdns_write_phy_reg(priv, SDHCI_CDNS_PHY_DLY_SD_DEFAULT, 4);
> +	sdhci_cdns_write_phy_reg(priv, SDHCI_CDNS_PHY_DLY_EMMC_LEGACY, 9);
> +	sdhci_cdns_write_phy_reg(priv, SDHCI_CDNS_PHY_DLY_EMMC_SDR, 2);
> +	sdhci_cdns_write_phy_reg(priv, SDHCI_CDNS_PHY_DLY_EMMC_DDR, 3);
> +}
> +
> +static inline void *sdhci_cdns_priv(struct sdhci_host *host)
> +{
> +	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
> +
> +	return sdhci_pltfm_priv(pltfm_host);
> +}
> +
> +static unsigned int sdhci_cdns_get_timeout_clock(struct sdhci_host *host)
> +{
> +	/*
> +	 * Cadence's spec says the Timeout Clock Frequency is the same as the
> +	 * Base Clock Frequency.  Divide it by 1000 to return a value in kHz.
> +	 */
> +	return host->max_clk / 1000;
> +}
> +
> +static void sdhci_cdns_set_uhs_signaling(struct sdhci_host *host,
> +					 unsigned int timing)
> +{
> +	struct sdhci_cdns_priv *priv = sdhci_cdns_priv(host);
> +	u32 mode, tmp;
> +
> +	switch (timing) {
> +	case MMC_TIMING_MMC_HS:
> +		mode = SDHCI_CDNS_HRS06_MODE_MMC_SDR;
> +		break;
> +	case MMC_TIMING_MMC_DDR52:
> +		mode = SDHCI_CDNS_HRS06_MODE_MMC_DDR;
> +		break;
> +	case MMC_TIMING_MMC_HS200:
> +		mode = SDHCI_CDNS_HRS06_MODE_MMC_HS200;
> +		break;
> +	case MMC_TIMING_MMC_HS400:
> +		mode = SDHCI_CDNS_HRS06_MODE_MMC_HS400;
> +		break;
> +	default:
> +		mode = SDHCI_CDNS_HRS06_MODE_SD;
> +		break;
> +	}
> +
> +	/* The speed mode for eMMC is selected by HRS06 register */
> +	tmp = readl(priv->hrs_addr + SDHCI_CDNS_HRS06);
> +	tmp &= ~SDHCI_CDNS_HRS06_MODE_MASK;
> +	tmp |= mode;
> +	writel(tmp, priv->hrs_addr + SDHCI_CDNS_HRS06);
> +
> +	/* For SD, fall back to the default handler */
> +	if (mode == SDHCI_CDNS_HRS06_MODE_SD)
> +		sdhci_set_uhs_signaling(host, timing);
> +}
> +
> +static const struct sdhci_ops sdhci_cdns_ops = {
> +	.set_clock = sdhci_set_clock,
> +	.get_timeout_clock = sdhci_cdns_get_timeout_clock,
> +	.set_bus_width = sdhci_set_bus_width,
> +	.reset = sdhci_reset,
> +	.set_uhs_signaling = sdhci_cdns_set_uhs_signaling,
> +};
> +
> +static const struct sdhci_pltfm_data sdhci_cdns_pltfm_data = {
> +	.ops = &sdhci_cdns_ops,
> +};
> +
> +static int sdhci_cdns_set_tune_val(struct sdhci_host *host, unsigned int val)
> +{
> +	struct sdhci_cdns_priv *priv = sdhci_cdns_priv(host);
> +	void __iomem *reg = priv->hrs_addr + SDHCI_CDNS_HRS06;
> +	u32 tmp;
> +
> +	if (WARN_ON(val > SDHCI_CDNS_HRS06_TUNE_MASK))
> +		return -EINVAL;
> +
> +	tmp = readl(reg);
> +	tmp &= ~(SDHCI_CDNS_HRS06_TUNE_MASK << SDHCI_CDNS_HRS06_TUNE_SHIFT);
> +	tmp |= val << SDHCI_CDNS_HRS06_TUNE_SHIFT;
> +	tmp |= SDHCI_CDNS_HRS06_TUNE_UP;
> +	writel(tmp, reg);
> +
> +	return readl_poll_timeout(reg, tmp, !(tmp & SDHCI_CDNS_HRS06_TUNE_UP),
> +				  0, 1);
> +}
> +
> +static int sdhci_cdns_execute_tuning(struct mmc_host *mmc, u32 opcode)
> +{
> +	struct sdhci_host *host = mmc_priv(mmc);
> +	int max_streak = 0;
> +	int cur_streak = 0;
> +	int end_of_streak, i;
> +
> +	/*
> +	 * This handler only implements the eMMC tuning that is specific to
> +	 * this controller.  Fall back to the standard method for SD timing.
> +	 */
> +	if (host->timing != MMC_TIMING_MMC_HS200)
> +		return sdhci_execute_tuning(mmc, opcode);
> +
> +	if (WARN_ON(opcode != MMC_SEND_TUNING_BLOCK_HS200))
> +		return -EINVAL;
> +
> +	for (i = 0; i < SDHCI_CDNS_MAX_TUNING_LOOP; i++) {
> +		if (sdhci_cdns_set_tune_val(host, i) ||
> +		    mmc_send_tuning(host->mmc, opcode, NULL)) { /* bad */
> +			cur_streak = 0;
> +		} else { /* good */
> +			cur_streak++;
> +			max_streak = max(max_streak, cur_streak);
> +			end_of_streak = i;
> +		}
> +	}
> +
> +	if (!max_streak) {
> +		dev_err(mmc_dev(host->mmc), "no tuning point found\n");
> +		return -EIO;
> +	}
> +
> +	return sdhci_cdns_set_tune_val(host, end_of_streak - max_streak / 2);
> +}
> +
> +static int sdhci_cdns_probe(struct platform_device *pdev)
> +{
> +	struct sdhci_host *host;
> +	struct sdhci_pltfm_host *pltfm_host;
> +	struct sdhci_cdns_priv *priv;
> +	struct clk *clk;
> +	int ret;
> +
> +	clk = devm_clk_get(&pdev->dev, NULL);
> +	if (IS_ERR(clk))
> +		return PTR_ERR(clk);
> +
> +	ret = clk_prepare_enable(clk);
> +	if (ret)
> +		return ret;
> +
> +	host = sdhci_pltfm_init(pdev, &sdhci_cdns_pltfm_data, sizeof(*priv));
> +	if (IS_ERR(host)) {
> +		ret = PTR_ERR(host);
> +		goto disable_clk;
> +	}
> +
> +	pltfm_host = sdhci_priv(host);
> +	pltfm_host->clk = clk;
> +
> +	priv = sdhci_cdns_priv(host);
> +	priv->hrs_addr = host->ioaddr;
> +	host->ioaddr += SDHCI_CDNS_SRS_BASE;
> +	host->mmc_host_ops.execute_tuning = sdhci_cdns_execute_tuning;
> +
> +	ret = mmc_of_parse(host->mmc);
> +	if (ret)
> +		goto free;
> +
> +	sdhci_cdns_phy_init(priv);
> +
> +	ret = sdhci_add_host(host);
> +	if (ret)
> +		goto free;
> +
> +	return 0;
> +free:
> +	sdhci_pltfm_free(pdev);
> +disable_clk:
> +	clk_disable_unprepare(clk);
> +
> +	return ret;
> +}
> +
> +static const struct of_device_id sdhci_cdns_match[] = {
> +	{ .compatible = "cdns,sd4hc" },
> +	{ /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(of, sdhci_cdns_match);
> +
> +static struct platform_driver sdhci_cdns_driver = {
> +	.driver = {
> +		.name = "sdhci-cdns",
> +		.pm = &sdhci_pltfm_pmops,
> +		.of_match_table = sdhci_cdns_match,
> +	},
> +	.probe = sdhci_cdns_probe,
> +	.remove = sdhci_pltfm_unregister,
> +};
> +module_platform_driver(sdhci_cdns_driver);
> +
> +MODULE_AUTHOR("Masahiro Yamada <yamada.masahiro@...ionext.com>");
> +MODULE_DESCRIPTION("Cadence SD/SDIO/eMMC Host Controller Driver");
> +MODULE_LICENSE("GPL");
> 

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