Re: [PATCH V6 1/2] PHY: Exynos: Add Exynos5250 SATA PHY driver

From: Yuvaraj Kumar
Date: Mon Jan 27 2014 - 08:38:35 EST

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On Fri, Jan 10, 2014 at 8:35 PM, Tomasz Figa <t.figa@xxxxxxxxxxx> wrote:
> Hi Yuvaraj,
>
> In general this version looks pretty good, but I have some questions inline.
>
> On 10.01.2014 08:00, Yuvaraj Kumar C D wrote:
> [snip]
>
>> diff --git a/drivers/phy/phy-exynos5250-sata-i2c.c
>> b/drivers/phy/phy-exynos5250-sata-i2c.c
>> new file mode 100644
>> index 0000000..206e337
>> --- /dev/null
>> +++ b/drivers/phy/phy-exynos5250-sata-i2c.c
>> @@ -0,0 +1,40 @@
>> +/*
>> + * Copyright (C) 2013 Samsung Electronics Co.Ltd
>> + * Author:
>> + * Yuvaraj C D <yuvaraj.cd@xxxxxxxxxxx>
>> + *
>> + * 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.
>> + *
>> + */
>> +
>> +#include <linux/i2c.h>
>> +#include <linux/kernel.h>
>> +#include <linux/module.h>
>> +
>> +static int exynos_sata_i2c_probe(struct i2c_client *client,
>> + const struct i2c_device_id *i2c_id)
>> +{
>> + return 0;
>> +}
>> +
>> +static const struct i2c_device_id sataphy_i2c_device_match[] = {
>> + { "exynos-sataphy-i2c", 0 },
>> +};
>> +
>> +static struct i2c_driver sataphy_i2c_driver = {
>> + .probe = exynos_sata_i2c_probe,
>> + .id_table = sataphy_i2c_device_match,
>> + .driver = {
>> + .name = "exynos-sataphy-i2c",
>> + .owner = THIS_MODULE,
>> + },
>> +};
>> +
>> +static int __init exynos5250_phy_i2c_init(void)
>> +{
>> + return i2c_add_driver(&sataphy_i2c_driver);
>> +}
>> +module_init(exynos5250_phy_i2c_init);
>
>
> Hmm, is this driver even necessary now?
>
> Wolfram, would it be possible to use an i2c_client without a driver bound to
> it?
>
>
>> diff --git a/drivers/phy/phy-exynos5250-sata.c
>> b/drivers/phy/phy-exynos5250-sata.c
>> new file mode 100644
>> index 0000000..6e5ff8d
>> --- /dev/null
>> +++ b/drivers/phy/phy-exynos5250-sata.c
>> @@ -0,0 +1,238 @@
>> +/*
>> + * Samsung SATA SerDes(PHY) driver
>> + *
>> + * Copyright (C) 2013 Samsung Electronics Co., Ltd.
>> + * Authors: Girish K S <ks.giri@xxxxxxxxxxx>
>> + * Yuvaraj Kumar C D <yuvaraj.cd@xxxxxxxxxxx>
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License version 2 as
>> + * published by the Free Software Foundation.
>> + */
>> +
>> +#include <linux/clk.h>
>> +#include <linux/delay.h>
>> +#include <linux/io.h>
>> +#include <linux/i2c.h>
>> +#include <linux/kernel.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>
>> +#include <linux/spinlock.h>
>> +#include <linux/mfd/syscon.h>
>> +
>> +#define EXYNOS5_SATA_RESET 0x4
>> +#define RESET_CMN_RST_N (1 << 1)
>> +#define LINK_RESET 0xF0000
>
>
> nit: Lowercase is preferred in hexadecimal notation.
> + all other occurrences in this file.
>
>
>> +#define EXYNOS5_SATA_MODE0 0x10
>> +#define EXYNOS5_SATAPHY_PMU_ENABLE (1 << 0)
>> +#define SATA_SPD_GEN3 (2 << 0)
>> +#define EXYNOS5_SATA_CTRL0 0x14
>> +#define CTRL0_P0_PHY_CALIBRATED_SEL (1 << 9)
>> +#define CTRL0_P0_PHY_CALIBRATED (1 << 8)
>> +#define EXYNOS5_SATA_PHSATA_CTRLM 0xE0
>> +#define PHCTRLM_REF_RATE (1 << 1)
>> +#define PHCTRLM_HIGH_SPEED (1 << 0)
>> +#define EXYNOS5_SATA_PHSATA_STATM 0xF0
>> +#define PHSTATM_PLL_LOCKED (1 << 0)
>> +#define EXYNOS_SATA_PHY_EN (1 << 0)
>> +#define SATAPHY_CONTROL_OFFSET 0x0724
>> +
>> +struct exynos_sata_phy {
>> + struct phy *phy;
>> + struct clk *phyclk;
>> + void __iomem *regs;
>> + void __iomem *pmureg;
>> + struct i2c_client *client;
>> +};
>> +
>> +static bool wait_for_reg_status(void __iomem *base, u32 reg, u32
>> checkbit,
>> + u32 status)
>> +{
>> + unsigned long timeout = jiffies + usecs_to_jiffies(1000);
>
>
> nit: It would be better to define the timeout using a macro to not use magic
> numbers.
>
>
>> +
>> + while (time_before(jiffies, timeout)) {
>> + if ((readl(base + reg) & checkbit) == status)
>> + return true;
>> + }
>> +
>> + return false;
>> +}
>> +
>> +static int exynos_sata_phy_power_on(struct phy *phy)
>> +{
>> + struct exynos_sata_phy *sata_phy = phy_get_drvdata(phy);
>> +
>> + regmap_update_bits(sata_phy->pmureg, SATAPHY_CONTROL_OFFSET,
>> + EXYNOS5_SATAPHY_PMU_ENABLE, EXYNOS_SATA_PHY_EN);
>
>
> regmap_update_bits can return an error. Wouldn't it be better to return it
> as return value of this function instead of returning 0 all the time? As a
> side effect, this would make the function smaller by two lines.
>
>
>> +
>> + return 0;
>> +}
>> +
>> +static int exynos_sata_phy_power_off(struct phy *phy)
>> +{
>> + struct exynos_sata_phy *sata_phy = phy_get_drvdata(phy);
>> +
>> + regmap_update_bits(sata_phy->pmureg, SATAPHY_CONTROL_OFFSET,
>> + EXYNOS5_SATAPHY_PMU_ENABLE, ~EXYNOS_SATA_PHY_EN);
>
>
> Same here.
>
>
>> +
>> + return 0;
>> +}
>> +
>> +static int exynos_sata_phy_init(struct phy *phy)
>> +{
>> + u32 val = 0;
>> + int ret = 0;
>> + u8 buf[] = { 0x3A, 0x0B };
>> + struct exynos_sata_phy *sata_phy = phy_get_drvdata(phy);
>> +
>> + regmap_update_bits(sata_phy->pmureg, SATAPHY_CONTROL_OFFSET,
>> + EXYNOS5_SATAPHY_PMU_ENABLE, EXYNOS_SATA_PHY_EN);
>
>
> regmap_update_bits returns an error code.
>
>
>> +
>> + writel(val, sata_phy->regs + EXYNOS5_SATA_RESET);
>> +
>> + val = readl(sata_phy->regs + EXYNOS5_SATA_RESET);
>> + val |= 0xFF;
>> + writel(val, sata_phy->regs + EXYNOS5_SATA_RESET);
>> +
>> + val = readl(sata_phy->regs + EXYNOS5_SATA_RESET);
>> + val |= LINK_RESET;
>> + writel(val, sata_phy->regs + EXYNOS5_SATA_RESET);
>> +
>> + val = readl(sata_phy->regs + EXYNOS5_SATA_RESET);
>> + val |= RESET_CMN_RST_N;
>> + writel(val, sata_phy->regs + EXYNOS5_SATA_RESET);
>> +
>> + val = readl(sata_phy->regs + EXYNOS5_SATA_PHSATA_CTRLM);
>> + val &= ~PHCTRLM_REF_RATE;
>> + writel(val, sata_phy->regs + EXYNOS5_SATA_PHSATA_CTRLM);
>> +
>> + /* High speed enable for Gen3 */
>> + val = readl(sata_phy->regs + EXYNOS5_SATA_PHSATA_CTRLM);
>> + val |= PHCTRLM_HIGH_SPEED;
>> + writel(val, sata_phy->regs + EXYNOS5_SATA_PHSATA_CTRLM);
>> +
>> + val = readl(sata_phy->regs + EXYNOS5_SATA_CTRL0);
>> + val |= CTRL0_P0_PHY_CALIBRATED_SEL | CTRL0_P0_PHY_CALIBRATED;
>> + writel(val, sata_phy->regs + EXYNOS5_SATA_CTRL0);
>> +
>> + val = readl(sata_phy->regs + EXYNOS5_SATA_MODE0);
>> + val |= SATA_SPD_GEN3;
>> + writel(val, sata_phy->regs + EXYNOS5_SATA_MODE0);
>> +
>> + ret = i2c_master_send(sata_phy->client, buf, sizeof(buf));
>> + if (ret < 0)
>> + return -ENXIO;
>
>
> Wouldn't it be better to return the same error code as i2c_master_send
> returned?
>
>
>> +
>> + /* release cmu reset */
>> + val = readl(sata_phy->regs + EXYNOS5_SATA_RESET);
>> + val &= ~RESET_CMN_RST_N;
>> + writel(val, sata_phy->regs + EXYNOS5_SATA_RESET);
>> +
>> + val = readl(sata_phy->regs + EXYNOS5_SATA_RESET);
>> + val |= RESET_CMN_RST_N;
>> + writel(val, sata_phy->regs + EXYNOS5_SATA_RESET);
>> +
>> + return (wait_for_reg_status(sata_phy->regs,
>> EXYNOS5_SATA_PHSATA_STATM,
>> + PHSTATM_PLL_LOCKED, 1)) ? 0 : -EINVAL;
>> +
>
>
> nit: Stray blank line.
>
> Also it might be more readable after making wait_for_reg_status() return an
> integer error code (0 and e.g. -EFAULT) and rewriting the last line to:
>
> ret = wait_for_reg_status(sata_phy->regs,
> EXYNOS5_SATA_PHSATA_STATM,
> PHSTATM_PLL_LOCKED, 1);
> if (ret < 0)
> dev_err(&sata_phy->client->dev,
> "PHY PLL locking failed\n");
>
> return ret;
>
> By the way, isn't this initialization really needed whenever the PHY is
> powered on?
>
>
>> +}
>> +
>> +static struct phy_ops exynos_sata_phy_ops = {
>> + .init = exynos_sata_phy_init,
>> + .power_on = exynos_sata_phy_power_on,
>> + .power_off = exynos_sata_phy_power_off,
>> + .owner = THIS_MODULE,
>> +};
>> +
>> +static int exynos_sata_phy_probe(struct platform_device *pdev)
>> +{
>> + struct exynos_sata_phy *sata_phy;
>> + struct device *dev = &pdev->dev;
>> + struct resource *res;
>> + struct phy_provider *phy_provider;
>> + struct device_node *node;
>> + int ret = 0;
>> +
>> + sata_phy = devm_kzalloc(dev, sizeof(*sata_phy), GFP_KERNEL);
>> + if (!sata_phy)
>> + return -ENOMEM;
>> +
>> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +
>> + sata_phy->regs = devm_ioremap_resource(dev, res);
>> + if (IS_ERR(sata_phy->regs))
>> + return PTR_ERR(sata_phy->regs);
>> +
>> + sata_phy->pmureg = syscon_regmap_lookup_by_phandle(dev->of_node,
>> + "samsung,syscon-phandle");
>
>
> pmureg is defined as (void __iomem *) in struct exynos_sata_phy, but
> syscon_regmap_lookup_by_phandle() returns (struct regmap *). Moreover it
> does not return NULL on error, but rather ERR_PTR(). Please correct this.
>
>
>> + if (!sata_phy->pmureg) {
>> + dev_err(dev, "syscon regmap lookup failed.\n");
>> + return PTR_ERR(sata_phy->pmureg);
>> + }
>> +
>> + node = of_parse_phandle(dev->of_node,
>> + "samsung,exynos-sataphy-i2c-phandle", 0);
>> + if (!node)
>> + return -ENODEV;
>
>
> An error here means that a required DT property was not specified or was
> specified incorrectly. IMHO -EINVAL would be better here.
>
>
>> +
>> + sata_phy->client = of_find_i2c_device_by_node(node);
>> + if (!sata_phy->client)
>> + return -EPROBE_DEFER;
>> +
>> + dev_set_drvdata(dev, sata_phy);
>> +
>> + sata_phy->phyclk = devm_clk_get(dev, "sata_phyctrl");
>> + if (IS_ERR(sata_phy->phyclk)) {
>> + dev_err(dev, "failed to get clk for PHY\n");
>> + return PTR_ERR(sata_phy->phyclk);
>> + }
>> +
>> + ret = clk_prepare_enable(sata_phy->phyclk);
>> + if (ret < 0) {
>> + dev_err(dev, "failed to enable source clk\n");
>> + return ret;
>> + }
>> +
>> + sata_phy->phy = devm_phy_create(dev, &exynos_sata_phy_ops, NULL);
>> + if (IS_ERR(sata_phy->phy)) {
>> + clk_disable_unprepare(sata_phy->phyclk);
>> + dev_err(dev, "failed to create PHY\n");
>> + return PTR_ERR(sata_phy->phy);
>> + }
>> +
>> + phy_set_drvdata(sata_phy->phy, sata_phy);
>> +
>> + phy_provider = devm_of_phy_provider_register(dev,
>> + of_phy_simple_xlate);
>> + if (IS_ERR(phy_provider)) {
>> + clk_disable_unprepare(sata_phy->phyclk);
>> + return PTR_ERR(phy_provider);
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static const struct of_device_id exynos_sata_phy_of_match[] = {
>> + { .compatible = "samsung,exynos5250-sata-phy" },
>> + { },
>> +};
>> +MODULE_DEVICE_TABLE(of, exynos_sata_phy_of_match);
>> +
>> +static struct platform_driver exynos_sata_phy_driver = {
>> + .probe = exynos_sata_phy_probe,
>
>
> If this driver can be compiled as module, don't you also need remove?
I tried this and found as such there is no resources hold by this
driver to handle in remove case.
This driver is used by ahci_platform driver and when load
phy-exynos5250-sata,driver usage count is 1.
so if we unload ahci_platform driver first and then
phy-exynos5250-sata.ko it cleanely unload this module.
>
> Best regards,
> Tomasz
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