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Message-id: <52D00C33.4060305@samsung.com>
Date: Fri, 10 Jan 2014 16:05:23 +0100
From: Tomasz Figa <t.figa@...sung.com>
To: Yuvaraj Kumar C D <yuvaraj.cd@...il.com>, kishon@...com,
kgene.kim@...sung.com, linux-kernel@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
linux-doc@...r.kernel.org, Wolfram Sang <wsa@...-dreams.de>
Cc: mark.rutland@....com, jg1.han@...sung.com,
b.zolnierkie@...sung.com, joshi@...sung.com, swarren@...dotorg.org,
grant.likely@...aro.org, christoffer.dall@...aro.org,
linux-ide@...r.kernel.org,
Yuvaraj Kumar C D <yuvaraj.cd@...sung.com>,
Girish K S <ks.giri@...sung.com>,
Vasanth Ananthan <vasanth.a@...sung.com>
Subject: Re: [PATCH V6 1/2] PHY: Exynos: Add Exynos5250 SATA PHY driver
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@...sung.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.
> + *
> + */
> +
> +#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@...sung.com>
> + * Yuvaraj Kumar C D <yuvaraj.cd@...sung.com>
> + *
> + * 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?
Best regards,
Tomasz
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