Re: [PATCH V6 1/2] PHY: Exynos: Add Exynos5250 SATA PHY driver
From: Tomasz Figa
Date: Fri Jan 10 2014 - 10:05:41 EST
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?
Best regards,
Tomasz
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