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Date:   Thu, 22 Aug 2019 16:08:48 +0300
From:   Andy Shevchenko <andriy.shevchenko@intel.com>
To:     "Ramuthevar,Vadivel MuruganX" 
        <vadivel.muruganx.ramuthevar@linux.intel.com>
Cc:     kishon@ti.com, robh@kernel.org, linux-kernel@vger.kernel.org,
        devicetree@vger.kernel.org, cheol.yong.kim@intel.com,
        qi-ming.wu@intel.com, peter.harliman.liem@intel.com
Subject: Re: [PATCH v4 2/2] phy: intel-lgm-emmc: Add support for eMMC PHY
Message-ID: <20190822130848.GO30120@smile.fi.intel.com>
References: <20190822102843.47964-1-vadivel.muruganx.ramuthevar@linux.intel.com>
 <20190822102843.47964-2-vadivel.muruganx.ramuthevar@linux.intel.com>
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On Thu, Aug 22, 2019 at 06:28:43PM +0800, Ramuthevar,Vadivel MuruganX wrote:
> From: Ramuthevar Vadivel Murugan <vadivel.muruganx.ramuthevar@linux.intel.com>
> 
> Add support for eMMC PHY on Intel's Lightning Mountain SoC.
> 

Thanks for an update!
One minor comment below. After addressing it
Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>

> Signed-off-by: Ramuthevar Vadivel Murugan <vadivel.muruganx.ramuthevar@linux.intel.com>
> ---
> chnages in v4:
>  - As per Andy's review comments,the following update
>  - add license_tag, macro, blank_line, error_check and grouping
> 
> changes in v3:
>  - As per Andy's review comments macro optimization,aligned
>    function call in proper order and udelay added.
> 
> changes in v2:
>  - optimize IS_CALDONE() and IS_DLLRDY() macro
>  - remove unneccessary comment
>  - remove redundant assignment
>  - add return the error ptr
> ---
>  drivers/phy/Kconfig                |   1 +
>  drivers/phy/Makefile               |   1 +
>  drivers/phy/intel/Kconfig          |   9 ++
>  drivers/phy/intel/Makefile         |   2 +
>  drivers/phy/intel/phy-intel-emmc.c | 281 +++++++++++++++++++++++++++++++++++++
>  5 files changed, 294 insertions(+)
>  create mode 100644 drivers/phy/intel/Kconfig
>  create mode 100644 drivers/phy/intel/Makefile
>  create mode 100644 drivers/phy/intel/phy-intel-emmc.c
> 
> diff --git a/drivers/phy/Kconfig b/drivers/phy/Kconfig
> index 0263db2ac874..b3ed94b98d9b 100644
> --- a/drivers/phy/Kconfig
> +++ b/drivers/phy/Kconfig
> @@ -69,5 +69,6 @@ source "drivers/phy/socionext/Kconfig"
>  source "drivers/phy/st/Kconfig"
>  source "drivers/phy/tegra/Kconfig"
>  source "drivers/phy/ti/Kconfig"
> +source "drivers/phy/intel/Kconfig"
>  
>  endmenu
> diff --git a/drivers/phy/Makefile b/drivers/phy/Makefile
> index 0d9fddc498a6..3f1fc9efbbed 100644
> --- a/drivers/phy/Makefile
> +++ b/drivers/phy/Makefile
> @@ -19,6 +19,7 @@ obj-y					+= broadcom/	\
>  					   cadence/	\
>  					   freescale/	\
>  					   hisilicon/	\
> +					   intel/	\
>  					   marvell/	\
>  					   motorola/	\
>  					   mscc/	\
> diff --git a/drivers/phy/intel/Kconfig b/drivers/phy/intel/Kconfig
> new file mode 100644
> index 000000000000..4ea6a8897cd7
> --- /dev/null
> +++ b/drivers/phy/intel/Kconfig
> @@ -0,0 +1,9 @@
> +# SPDX-License-Identifier: GPL-2.0
> +#
> +# Phy drivers for Intel Lightning Mountain(LGM) platform
> +#
> +config PHY_INTEL_EMMC
> +	tristate "Intel EMMC PHY driver"
> +	select GENERIC_PHY
> +	help
> +	  Enable this to support the Intel EMMC PHY
> diff --git a/drivers/phy/intel/Makefile b/drivers/phy/intel/Makefile
> new file mode 100644
> index 000000000000..6b876a75599d
> --- /dev/null
> +++ b/drivers/phy/intel/Makefile
> @@ -0,0 +1,2 @@
> +# SPDX-License-Identifier: GPL-2.0
> +obj-$(CONFIG_PHY_INTEL_EMMC)            += phy-intel-emmc.o
> diff --git a/drivers/phy/intel/phy-intel-emmc.c b/drivers/phy/intel/phy-intel-emmc.c
> new file mode 100644
> index 000000000000..4f0226f37ab0
> --- /dev/null
> +++ b/drivers/phy/intel/phy-intel-emmc.c
> @@ -0,0 +1,281 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Intel eMMC PHY driver
> + * Copyright (C) 2019 Intel, Corp.
> + */
> +
> +#include <linux/bits.h>
> +#include <linux/clk.h>
> +#include <linux/delay.h>
> +#include <linux/mfd/syscon.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_address.h>
> +#include <linux/phy/phy.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +
> +/* eMMC phy register definitions */
> +#define EMMC_PHYCTRL0_REG	0xa8
> +#define DR_TY_MASK		GENMASK(30, 28)
> +#define DR_TY_SHIFT(x)		(((x) << 28) & DR_TY_MASK)
> +#define OTAPDLYENA		BIT(14)
> +#define OTAPDLYSEL_MASK		GENMASK(13, 10)
> +#define OTAPDLYSEL_SHIFT(x)	(((x) << 10) & OTAPDLYSEL_MASK)
> +
> +#define EMMC_PHYCTRL1_REG	0xac
> +#define PDB_MASK		BIT(0)
> +#define PDB_SHIFT(x)		(((x) << 0) & PDB_MASK)
> +#define ENDLL_MASK		BIT(7)
> +#define ENDLL_SHIFT(x)		(((x) << 7) & ENDLL_MASK)
> +
> +#define EMMC_PHYCTRL2_REG	0xb0
> +#define FRQSEL_25M		0
> +#define FRQSEL_50M		1
> +#define FRQSEL_100M		2
> +#define FRQSEL_150M		3
> +#define FRQSEL_MASK		GENMASK(24, 22)
> +#define FRQSEL_SHIFT(x)		(((x) << 22) & FRQSEL_MASK)
> +
> +#define EMMC_PHYSTAT_REG	0xbc
> +#define CALDONE_MASK		BIT(9)
> +#define DLLRDY_MASK		BIT(8)
> +#define IS_CALDONE(x)	((x) & CALDONE_MASK)
> +#define IS_DLLRDY(x)	((x) & DLLRDY_MASK)
> +
> +struct intel_emmc_phy {
> +	struct regmap *syscfg;
> +	struct clk *emmcclk;
> +};
> +
> +static int intel_emmc_phy_power(struct phy *phy, bool on_off)
> +{
> +	struct intel_emmc_phy *priv = phy_get_drvdata(phy);
> +	unsigned int caldone;
> +	unsigned int dllrdy;
> +	unsigned int freqsel;
> +	unsigned long rate;
> +	int ret, quot;
> +
> +	/*
> +	 * Keep phyctrl_pdb and phyctrl_endll low to allow
> +	 * initialization of CALIO state M/C DFFs
> +	 */
> +	ret = regmap_update_bits(priv->syscfg, EMMC_PHYCTRL1_REG, PDB_MASK,
> +				 PDB_SHIFT(0));
> +	if (ret) {
> +		dev_err(&phy->dev, "CALIO power down bar failed: %d\n", ret);
> +		return ret;
> +	}
> +
> +	/* Already finish power_off above */
> +	if (!on_off)
> +		return 0;
> +
> +	rate = clk_get_rate(priv->emmcclk);
> +	quot = DIV_ROUND_CLOSEST(rate, 50000000);
> +	if (quot > FRQSEL_150M)
> +		dev_warn(&phy->dev, "Unsupported rate: %lu\n", rate);
> +	freqsel = clamp_t(int, quot, FRQSEL_25M, FRQSEL_150M);
> +
> +	/*
> +	 * According to the user manual, calpad calibration
> +	 * cycle takes more than 2us without the minimal recommended
> +	 * value, so we may need a little margin here
> +	 */
> +	udelay(5);
> +
> +	ret = regmap_update_bits(priv->syscfg, EMMC_PHYCTRL1_REG, PDB_MASK, 1);

1 is magic.

> +	if (ret) {
> +		dev_err(&phy->dev, "CALIO power down bar failed: %d\n", ret);
> +		return ret;
> +	}
> +
> +	/*
> +	 * According to the user manual, it asks driver to wait 5us for
> +	 * calpad busy trimming. However it is documented that this value is
> +	 * PVT(A.K.A process,voltage and temperature) relevant, so some
> +	 * failure cases are found which indicates we should be more tolerant
> +	 * to calpad busy trimming.
> +	 */
> +	ret = regmap_read_poll_timeout(priv->syscfg, EMMC_PHYSTAT_REG,
> +				       caldone, IS_CALDONE(caldone),
> +				       0, 50);
> +	if (ret) {
> +		dev_err(&phy->dev, "caldone failed, ret=%d\n", ret);
> +		return ret;
> +	}
> +
> +	/* Set the frequency of the DLL operation */
> +	ret = regmap_update_bits(priv->syscfg, EMMC_PHYCTRL2_REG, FRQSEL_MASK,
> +				 FRQSEL_SHIFT(freqsel));
> +	if (ret) {
> +		dev_err(&phy->dev, "set the frequency of dll failed:%d\n", ret);
> +		return ret;
> +	}
> +
> +	/* Turn on the DLL */
> +	ret = regmap_update_bits(priv->syscfg, EMMC_PHYCTRL1_REG, ENDLL_MASK,
> +				 ENDLL_SHIFT(1));
> +	if (ret) {
> +		dev_err(&phy->dev, "turn on the dll failed: %d\n", ret);
> +		return ret;
> +	}
> +
> +	/*
> +	 * After enabling analog DLL circuits docs say that we need 10.2 us if
> +	 * our source clock is at 50 MHz and that lock time scales linearly
> +	 * with clock speed.  If we are powering on the PHY and the card clock
> +	 * is super slow (like 100 kHZ) this could take as long as 5.1 ms as
> +	 * per the math: 10.2 us * (50000000 Hz / 100000 Hz) => 5.1 ms
> +	 * Hopefully we won't be running at 100 kHz, but we should still make
> +	 * sure we wait long enough.
> +	 *
> +	 * NOTE: There appear to be corner cases where the DLL seems to take
> +	 * extra long to lock for reasons that aren't understood.  In some
> +	 * extreme cases we've seen it take up to over 10ms (!).  We'll be
> +	 * generous and give it 50ms.
> +	 */
> +	ret = regmap_read_poll_timeout(priv->syscfg,
> +				       EMMC_PHYSTAT_REG,
> +				       dllrdy, IS_DLLRDY(dllrdy),
> +				       0, 50 * USEC_PER_MSEC);
> +	if (ret) {
> +		dev_err(&phy->dev, "dllrdy failed. ret=%d\n", ret);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static int intel_emmc_phy_init(struct phy *phy)
> +{
> +	struct intel_emmc_phy *priv = phy_get_drvdata(phy);
> +
> +	/*
> +	 * We purposely get the clock here and not in probe to avoid the
> +	 * circular dependency problem. We expect:
> +	 * - PHY driver to probe
> +	 * - SDHCI driver to start probe
> +	 * - SDHCI driver to register it's clock
> +	 * - SDHCI driver to get the PHY
> +	 * - SDHCI driver to init the PHY
> +	 *
> +	 * The clock is optional, so upon any error just return it like
> +	 * any other error to user.
> +	 *
> +	 */
> +	priv->emmcclk = clk_get_optional(&phy->dev, "emmcclk");
> +	if (IS_ERR(priv->emmcclk)) {
> +		dev_err(&phy->dev, "ERROR: getting emmcclk\n");
> +		return PTR_ERR(priv->emmcclk);
> +	}
> +
> +	return 0;
> +}
> +
> +static int intel_emmc_phy_exit(struct phy *phy)
> +{
> +	struct intel_emmc_phy *priv = phy_get_drvdata(phy);
> +
> +	clk_put(priv->emmcclk);
> +
> +	return 0;
> +}
> +
> +static int intel_emmc_phy_power_on(struct phy *phy)
> +{
> +	struct intel_emmc_phy *priv = phy_get_drvdata(phy);
> +	int ret;
> +
> +	/* Drive impedance: 50 Ohm */
> +	ret = regmap_update_bits(priv->syscfg, EMMC_PHYCTRL0_REG, DR_TY_MASK,
> +				 DR_TY_SHIFT(6));
> +	if (ret) {
> +		dev_err(&phy->dev, "ERROR set drive-impednce-50ohm: %d\n", ret);
> +		return ret;
> +	}
> +
> +	/* Output tap delay: disable */
> +	ret = regmap_update_bits(priv->syscfg, EMMC_PHYCTRL0_REG, OTAPDLYENA, 0);
> +	if (ret) {
> +		dev_err(&phy->dev, "ERROR Set output tap delay : %d\n", ret);
> +		return ret;
> +	}
> +
> +	/* Output tap delay */
> +	ret = regmap_update_bits(priv->syscfg, EMMC_PHYCTRL0_REG,
> +				 OTAPDLYSEL_MASK, OTAPDLYSEL_SHIFT(4));
> +	if (ret) {
> +		dev_err(&phy->dev, "ERROR: output tap dly select: %d\n", ret);
> +		return ret;
> +	}
> +
> +	/* Power up eMMC phy analog blocks */
> +	return intel_emmc_phy_power(phy, true);
> +}
> +
> +static int intel_emmc_phy_power_off(struct phy *phy)
> +{
> +	/* Power down eMMC phy analog blocks */
> +	return intel_emmc_phy_power(phy, false);
> +}
> +
> +static const struct phy_ops ops = {
> +	.init		= intel_emmc_phy_init,
> +	.exit		= intel_emmc_phy_exit,
> +	.power_on	= intel_emmc_phy_power_on,
> +	.power_off	= intel_emmc_phy_power_off,
> +	.owner		= THIS_MODULE,
> +};
> +
> +static int intel_emmc_phy_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct device_node *np = dev->of_node;
> +	struct intel_emmc_phy *priv;
> +	struct phy *generic_phy;
> +	struct phy_provider *phy_provider;
> +
> +	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	/* Get eMMC phy (accessed via chiptop) regmap */
> +	priv->syscfg = syscon_regmap_lookup_by_phandle(np, "intel,syscon");
> +	if (IS_ERR(priv->syscfg)) {
> +		dev_err(dev, "failed to find syscon\n");
> +		return PTR_ERR(priv->syscfg);
> +	}
> +
> +	generic_phy = devm_phy_create(dev, np, &ops);
> +	if (IS_ERR(generic_phy)) {
> +		dev_err(dev, "failed to create PHY\n");
> +		return PTR_ERR(generic_phy);
> +	}
> +
> +	phy_set_drvdata(generic_phy, priv);
> +	phy_provider = devm_of_phy_provider_register(dev, of_phy_simple_xlate);
> +
> +	return PTR_ERR_OR_ZERO(phy_provider);
> +}
> +
> +static const struct of_device_id intel_emmc_phy_dt_ids[] = {
> +	{ .compatible = "intel,lgm-emmc-phy" },
> +	{}
> +};
> +
> +MODULE_DEVICE_TABLE(of, intel_emmc_phy_dt_ids);
> +
> +static struct platform_driver intel_emmc_driver = {
> +	.probe		= intel_emmc_phy_probe,
> +	.driver		= {
> +		.name	= "intel-emmc-phy",
> +		.of_match_table = intel_emmc_phy_dt_ids,
> +	},
> +};
> +
> +module_platform_driver(intel_emmc_driver);
> +
> +MODULE_AUTHOR("Peter Harliman Liem <peter.harliman.liem@intel.com>");
> +MODULE_DESCRIPTION("Intel eMMC PHY driver");
> -- 
> 2.11.0
> 

-- 
With Best Regards,
Andy Shevchenko