Re: [PATCH v9 3/4] phy: Add new Exynos USB 2.0 PHY driver
From: Kishon Vijay Abraham I
Date: Thu Mar 06 2014 - 03:57:13 EST
Hi,
On Thursday 06 March 2014 02:22 PM, Anton Tikhomirov wrote:
Hello,
Subject: Re: [PATCH v9 3/4] phy: Add new Exynos USB 2.0 PHY driver
On Thursday 06 March 2014 01:56 PM, Anton Tikhomirov wrote:
Hi Kamil,
...
+| 3. Supporting SoCs
++--------------------
+
+To support a new SoC a new file should be added to the drivers/phy
+directory. Each SoC's configuration is stored in an instance of the
+struct samsung_usb2_phy_config.
+
+struct samsung_usb2_phy_config {
+ const struct samsung_usb2_common_phy *phys;
+ unsigned int num_phys;
+ bool has_mode_switch;
You missed rate_to_clk here.
+};
+
...
diff --git a/drivers/phy/phy-samsung-usb2.c b/drivers/phy/phy-
samsung-
usb2.c
new file mode 100644
index 0000000..c3b7719
--- /dev/null
+++ b/drivers/phy/phy-samsung-usb2.c
@@ -0,0 +1,222 @@
+/*
+ * Samsung SoC USB 1.1/2.0 PHY driver
+ *
+ * Copyright (C) 2013 Samsung Electronics Co., Ltd.
+ * Author: Kamil Debski <k.debski@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/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/spinlock.h>
+#include "phy-samsung-usb2.h"
+
+static int samsung_usb2_phy_power_on(struct phy *phy)
+{
+ struct samsung_usb2_phy_instance *inst = phy_get_drvdata(phy);
+ struct samsung_usb2_phy_driver *drv = inst->drv;
+ int ret;
+
+ dev_dbg(drv->dev, "Request to power_on \"%s\" usb phy\n",
+ inst->cfg->label);
+ ret = clk_prepare_enable(drv->clk);
clk_prepare_enable() can sleep, and therefore doesn't allow
samusng_usb2_phy_power_on() to be used in atomic context
(e.g. inside spin_lock-ed area), what sometimes may be desirable.
What about to prepare clock in probe, and just enable it here
(note: clk_enable() doesn't sleep).
The PHY power-on callback is anyway called with mutex held, so I guess
it's fine to have clk_prepare_enable() here.
If we rely totally on generic PHY functions such as phy_power_on()
and friends, why do we need to use locking in callbacks at all.
Didn't get you.. We don't want to invoke power_on when init is getting
executed or you don't want power on or power off to get executed
simultaneously right? So we need to protect it.
Cheers
Kishon
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