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    SubjectRe: [RFC 04/12] phy: Add simple-phy driver
    Hi,

    On Monday 21 October 2013 07:48 PM, Tomasz Stanislawski wrote:
    > Add simple-phy driver to support a single register
    > PHY interfaces present on Exynos4 SoC.

    How are these PHY interfaces modelled in the SoC? Where does the register
    actually reside?
    >
    > Signed-off-by: Tomasz Stanislawski <t.stanislaws@samsung.com>
    > ---
    > drivers/phy/Kconfig | 5 ++
    > drivers/phy/Makefile | 1 +
    > drivers/phy/phy-simple.c | 128 ++++++++++++++++++++++++++++++++++++++++++++++
    > 3 files changed, 134 insertions(+)
    > create mode 100644 drivers/phy/phy-simple.c
    >
    > diff --git a/drivers/phy/Kconfig b/drivers/phy/Kconfig
    > index ac239ac..619c657 100644
    > --- a/drivers/phy/Kconfig
    > +++ b/drivers/phy/Kconfig
    > @@ -38,4 +38,9 @@ config TWL4030_USB
    > This transceiver supports high and full speed devices plus,
    > in host mode, low speed.
    >
    > +config PHY_SIMPLE
    > + tristate "Simple PHY driver"

    This is too generic a name to be used. Lets name it something specific to what
    it is used for (EXYNOS/HDMI.. ?).
    > + help
    > + Support for PHY controllers configured using single register.
    > +
    > endmenu
    > diff --git a/drivers/phy/Makefile b/drivers/phy/Makefile
    > index 0dd8a98..3d68e19 100644
    > --- a/drivers/phy/Makefile
    > +++ b/drivers/phy/Makefile
    > @@ -5,3 +5,4 @@
    > obj-$(CONFIG_GENERIC_PHY) += phy-core.o
    > obj-$(CONFIG_OMAP_USB2) += phy-omap-usb2.o
    > obj-$(CONFIG_TWL4030_USB) += phy-twl4030-usb.o
    > +obj-$(CONFIG_PHY_SIMPLE) += phy-simple.o
    > diff --git a/drivers/phy/phy-simple.c b/drivers/phy/phy-simple.c
    > new file mode 100644
    > index 0000000..4a28af7
    > --- /dev/null
    > +++ b/drivers/phy/phy-simple.c
    > @@ -0,0 +1,128 @@
    > +/*
    > + * Simple PHY driver
    > + *
    > + * Copyright (C) 2013 Samsung Electronics Co., Ltd.
    > + * Author: Tomasz Stanislawski <t.stanislaws@samsung.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/io.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/spinlock.h>
    > +
    > +struct simple_phy {
    > + spinlock_t slock;
    > + u32 on_value;
    > + u32 off_value;
    > + u32 mask;
    > + void __iomem *regs;
    > +};
    > +
    > +static int sphy_set(struct simple_phy *sphy, bool on)
    > +{
    > + u32 reg;
    > +
    > + spin_lock(&sphy->slock);

    Lets add spin_lock only when it is absolutely necessary. When your PHY provider
    implements only a single PHY, it is not needed. phy_power_on and phy_power_off
    is already protected by the framework.
    > +
    > + reg = readl(sphy->regs);
    > + reg &= ~sphy->mask;
    > + reg |= sphy->mask & (on ? sphy->on_value : sphy->off_value);
    > + writel(reg, sphy->regs);
    > +
    > + spin_unlock(&sphy->slock);
    > +
    > + return 0;
    > +}
    > +
    > +static int simple_phy_power_on(struct phy *phy)
    > +{
    > + return sphy_set(phy_get_drvdata(phy), 1);
    > +}
    > +
    > +static int simple_phy_power_off(struct phy *phy)
    > +{
    > + return sphy_set(phy_get_drvdata(phy), 0);
    > +}
    > +
    > +static struct phy_ops simple_phy_ops = {
    > + .power_on = simple_phy_power_on,
    > + .power_off = simple_phy_power_off,
    > + .owner = THIS_MODULE,
    > +};
    > +
    > +static int simple_phy_probe(struct platform_device *pdev)
    > +{
    > + struct device *dev = &pdev->dev;
    > + struct simple_phy *sphy;
    > + struct resource *res;
    > + struct phy_provider *phy_provider;
    > + struct phy *phy;
    > +
    > + sphy = devm_kzalloc(dev, sizeof(*sphy), GFP_KERNEL);
    > + if (!sphy)
    > + return -ENOMEM;
    > +
    > + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
    > +
    > + sphy->regs = devm_ioremap_resource(dev, res);
    > + if (IS_ERR(sphy->regs)) {
    > + dev_err(dev, "failed to ioremap registers\n");
    > + return PTR_ERR(sphy->regs);
    > + }
    > +
    > + spin_lock_init(&sphy->slock);
    > +
    > + phy_provider = devm_of_phy_provider_register(dev, NULL);

    pass 'of_phy_simple_xlate' instead of NULL.
    > + if (IS_ERR(phy_provider)) {
    > + dev_err(dev, "failed to register PHY provider\n");
    > + return PTR_ERR(phy_provider);
    > + }
    > +
    > + phy = devm_phy_create(dev, &simple_phy_ops, NULL);
    > + if (IS_ERR(phy)) {
    > + dev_err(dev, "failed to create PHY\n");
    > + return PTR_ERR(phy);
    > + }
    > +
    > + sphy->mask = 1;
    > + sphy->on_value = ~0;
    > + sphy->off_value = 0;
    > +
    > + of_property_read_u32(dev->of_node, "mask", &sphy->mask);

    This means your driver will depend on dt data to describe how the register
    should look like. Not a good idea.
    > + of_property_read_u32(dev->of_node, "on-value", &sphy->on_value);
    > + of_property_read_u32(dev->of_node, "off-value", &sphy->off_value);
    > +
    > + phy_set_drvdata(phy, sphy);
    > +
    > + dev_info(dev, "probe successful\n");
    Lets not make the boot noisy.

    Thanks
    Kishon


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