[PATCH 6/6] clk: Add initial WM831x clock driver

Mark Brown
2011-07-11T02:53:57Z

The WM831x and WM832x series of PMICs contain a flexible clocking
subsystem intended to provide always on and system core clocks. It
features:

- A 32.768kHz crystal oscillator which can optionally be used to pass
through an externally generated clock.
- A FLL which can be clocked from either the 32.768kHz oscillator or
the CLKIN pin.
- A CLKOUT pin which can bring out either the oscillator or the FLL
output.
- The 32.768kHz clock can also optionally be brought out on the GPIO
pins of the device.

This driver fully supports the 32.768kHz oscillator and CLKOUT. The FLL
is supported only in AUTO mode, the full flexibility of the FLL cannot
currently be used. The use of clock references other than the internal
oscillator is not currently supported, and since clk_set_parent() is not
implemented in the generic clock API the clock tree configuration cannot
be changed at runtime.

Due to a lack of access to systems where the core SoC has been converted
to use the generic clock API this driver has been compile tested only.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
---
MAINTAINERS | 1 +
drivers/clk/Kconfig | 5 +
drivers/clk/Makefile | 1 +
drivers/clk/clk-wm831x.c | 389 ++++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 396 insertions(+), 0 deletions(-)
create mode 100644 drivers/clk/clk-wm831x.c

diff --git a/MAINTAINERS b/MAINTAINERS
index ae563fa..c234756 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -6969,6 +6969,7 @@ T: git git://opensource.wolfsonmicro.com/linux-2.6-audioplus
W: http://opensource.wolfsonmicro.com/content/linux-drivers-wolfson-devices
S: Supported
F: Documentation/hwmon/wm83??
+F: drivers/clk/clk-wm83*.c
F: drivers/leds/leds-wm83*.c
F: drivers/mfd/wm8*.c
F: drivers/power/wm83*.c
diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig
index 1fd0070..7f6eec2 100644
--- a/drivers/clk/Kconfig
+++ b/drivers/clk/Kconfig
@@ -10,6 +10,7 @@ config GENERIC_CLK_BUILD_TEST
depends on EXPERIMENTAL && GENERIC_CLK
select GENERIC_CLK_FIXED
select GENERIC_CLK_GATE
+ select GENERIC_CLK_WM831X if MFD_WM831X=y
help
Enable all possible generic clock drivers. This is only
useful for improving build coverage, it is not useful for
@@ -22,3 +23,7 @@ config GENERIC_CLK_FIXED
config GENERIC_CLK_GATE
bool
depends on GENERIC_CLK
+
+config GENERIC_CLK_WM831X
+ tristate
+ depends on GENERIC_CLK && MFD_WM831X
diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
index d186446..6628ad5 100644
--- a/drivers/clk/Makefile
+++ b/drivers/clk/Makefile
@@ -3,3 +3,4 @@ obj-$(CONFIG_CLKDEV_LOOKUP) += clkdev.o
obj-$(CONFIG_GENERIC_CLK) += clk.o
obj-$(CONFIG_GENERIC_CLK_FIXED) += clk-fixed.o
obj-$(CONFIG_GENERIC_CLK_GATE) += clk-gate.o
+obj-$(CONFIG_GENERIC_CLK_WM831X) += clk-wm831x.o
diff --git a/drivers/clk/clk-wm831x.c b/drivers/clk/clk-wm831x.c
new file mode 100644
index 0000000..82782f1
--- /dev/null
+++ b/drivers/clk/clk-wm831x.c
@@ -0,0 +1,389 @@
+/*
+ * WM831x clock control
+ *
+ * Copyright 2011 Wolfson Microelectronics PLC.
+ *
+ * Author: Mark Brown <broonie@opensource.wolfsonmicro.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/clk.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/platform_device.h>
+#include <linux/mfd/wm831x/core.h>
+
+struct wm831x_clk {
+ struct wm831x *wm831x;
+ struct clk_hw xtal_hw;
+ struct clk_hw fll_hw;
+ struct clk_hw clkout_hw;
+ bool xtal_ena;
+};
+
+static int wm831x_xtal_enable(struct clk_hw *hw)
+{
+ struct wm831x_clk *clkdata = container_of(hw, struct wm831x_clk,
+ xtal_hw);
+
+ if (clkdata->xtal_ena)
+ return 0;
+ else
+ return -EPERM;
+}
+
+static unsigned long wm831x_xtal_recalc_rate(struct clk_hw *hw)
+{
+ struct wm831x_clk *clkdata = container_of(hw, struct wm831x_clk,
+ xtal_hw);
+
+ if (clkdata->xtal_ena)
+ return 32768;
+ else
+ return 0;
+}
+
+static long wm831x_xtal_round_rate(struct clk_hw *hw, unsigned long rate)
+{
+ return wm831x_xtal_recalc_rate(hw);
+}
+
+static const struct clk_hw_ops wm831x_xtal_ops = {
+ .enable = wm831x_xtal_enable,
+ .recalc_rate = wm831x_xtal_recalc_rate,
+ .round_rate = wm831x_xtal_round_rate,
+};
+
+static const unsigned long wm831x_fll_auto_rates[] = {
+ 2048000,
+ 11289600,
+ 12000000,
+ 12288000,
+ 19200000,
+ 22579600,
+ 24000000,
+ 24576000,
+};
+
+static bool wm831x_fll_enabled(struct wm831x *wm831x)
+{
+ int ret;
+
+ ret = wm831x_reg_read(wm831x, WM831X_FLL_CONTROL_1);
+ if (ret < 0) {
+ dev_err(wm831x->dev, "Unable to read FLL_CONTROL_1: %d\n",
+ ret);
+ return true;
+ }
+
+ if (ret & WM831X_FLL_ENA)
+ return true;
+ else
+ return false;
+}
+
+static int wm831x_fll_prepare(struct clk_hw *hw)
+{
+ struct wm831x_clk *clkdata = container_of(hw, struct wm831x_clk,
+ fll_hw);
+ struct wm831x *wm831x = clkdata->wm831x;
+ int ret;
+
+ ret = wm831x_set_bits(wm831x, WM831X_FLL_CONTROL_2,
+ WM831X_FLL_ENA, WM831X_FLL_ENA);
+ if (ret != 0)
+ dev_crit(wm831x->dev, "Failed to enable FLL: %d\n", ret);
+
+ return ret;
+}
+
+static void wm831x_fll_unprepare(struct clk_hw *hw)
+{
+ struct wm831x_clk *clkdata = container_of(hw, struct wm831x_clk,
+ fll_hw);
+ struct wm831x *wm831x = clkdata->wm831x;
+ int ret;
+
+ ret = wm831x_set_bits(wm831x, WM831X_FLL_CONTROL_2, WM831X_FLL_ENA, 0);
+ if (ret != 0)
+ dev_crit(wm831x->dev, "Failed to disaable FLL: %d\n", ret);
+}
+
+static unsigned long wm831x_fll_recalc_rate(struct clk_hw *hw)
+{
+ struct wm831x_clk *clkdata = container_of(hw, struct wm831x_clk,
+ fll_hw);
+ struct wm831x *wm831x = clkdata->wm831x;
+ int ret;
+
+ ret = wm831x_reg_read(wm831x, WM831X_CLOCK_CONTROL_2);
+ if (ret < 0) {
+ dev_err(wm831x->dev, "Unable to read CLOCK_CONTROL_2: %d\n",
+ ret);
+ return 0;
+ }
+
+ if (ret & WM831X_FLL_AUTO)
+ return wm831x_fll_auto_rates[ret & WM831X_FLL_AUTO_FREQ_MASK];
+
+ dev_err(wm831x->dev, "FLL only supported in AUTO mode\n");
+ return 0;
+}
+
+static int wm831x_fll_set_rate(struct clk_hw *hw, unsigned long rate,
+ unsigned long *parent_rate)
+{
+ struct wm831x_clk *clkdata = container_of(hw, struct wm831x_clk,
+ fll_hw);
+ struct wm831x *wm831x = clkdata->wm831x;
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(wm831x_fll_auto_rates); i++)
+ if (wm831x_fll_auto_rates[i] = rate)
+ break;
+ if (i = ARRAY_SIZE(wm831x_fll_auto_rates))
+ return -EINVAL;
+
+ if (wm831x_fll_enabled(wm831x))
+ return -EPERM;
+
+ return wm831x_set_bits(wm831x, WM831X_CLOCK_CONTROL_2,
+ WM831X_FLL_AUTO_FREQ_MASK, i);
+}
+
+static struct clk *wm831x_fll_get_parent(struct clk_hw *hw)
+{
+ struct wm831x_clk *clkdata = container_of(hw, struct wm831x_clk,
+ fll_hw);
+ struct wm831x *wm831x = clkdata->wm831x;
+ int ret;
+
+ /* AUTO mode is always clocked from the crystal */
+ ret = wm831x_reg_read(wm831x, WM831X_CLOCK_CONTROL_2);
+ if (ret < 0) {
+ dev_err(wm831x->dev, "Unable to read CLOCK_CONTROL_2: %d\n",
+ ret);
+ return NULL;
+ }
+
+ if (ret & WM831X_FLL_AUTO)
+ return clkdata->xtal_hw.clk;
+
+ ret = wm831x_reg_read(wm831x, WM831X_FLL_CONTROL_5);
+ if (ret < 0) {
+ dev_err(wm831x->dev, "Unable to read FLL_CONTROL_5: %d\n",
+ ret);
+ return NULL;
+ }
+
+ switch (ret & WM831X_FLL_CLK_SRC_MASK) {
+ case 0:
+ return clkdata->xtal_hw.clk;
+ case 1:
+ dev_warn(wm831x->dev,
+ "FLL clocked from CLKIN not yet supported\n");
+ return NULL;
+ default:
+ dev_err(wm831x->dev, "Unsupported FLL clock source %d\n",
+ ret & WM831X_FLL_CLK_SRC_MASK);
+ return NULL;
+ }
+}
+
+static const struct clk_hw_ops wm831x_fll_ops = {
+ .prepare = wm831x_fll_prepare,
+ .unprepare = wm831x_fll_unprepare,
+ .recalc_rate = wm831x_fll_recalc_rate,
+ .set_rate = wm831x_fll_set_rate,
+ .get_parent = wm831x_fll_get_parent,
+};
+
+static int wm831x_clkout_prepare(struct clk_hw *hw)
+{
+ struct wm831x_clk *clkdata = container_of(hw, struct wm831x_clk,
+ clkout_hw);
+ struct wm831x *wm831x = clkdata->wm831x;
+ int ret;
+
+ ret = wm831x_reg_unlock(wm831x);
+ if (ret != 0) {
+ dev_crit(wm831x->dev, "Failed to lock registers: %d\n", ret);
+ return ret;
+ }
+
+ ret = wm831x_set_bits(wm831x, WM831X_CLOCK_CONTROL_1,
+ WM831X_CLKOUT_ENA, WM831X_CLKOUT_ENA);
+ if (ret != 0)
+ dev_crit(wm831x->dev, "Failed to enable CLKOUT: %d\n", ret);
+
+ wm831x_reg_lock(wm831x);
+
+ return ret;
+}
+
+static void wm831x_clkout_unprepare(struct clk_hw *hw)
+{
+ struct wm831x_clk *clkdata = container_of(hw, struct wm831x_clk,
+ clkout_hw);
+ struct wm831x *wm831x = clkdata->wm831x;
+ int ret;
+
+ ret = wm831x_reg_unlock(wm831x);
+ if (ret != 0) {
+ dev_crit(wm831x->dev, "Failed to lock registers: %d\n", ret);
+ return;
+ }
+
+ ret = wm831x_set_bits(wm831x, WM831X_CLOCK_CONTROL_1,
+ WM831X_CLKOUT_ENA, 0);
+ if (ret != 0)
+ dev_crit(wm831x->dev, "Failed to disable CLKOUT: %d\n", ret);
+
+ wm831x_reg_lock(wm831x);
+}
+
+static unsigned long wm831x_clkout_recalc_rate(struct clk_hw *hw)
+{
+ return clk_get_rate(clk_get_parent(hw->clk));
+}
+
+static long wm831x_clkout_round_rate(struct clk_hw *hw, unsigned long rate)
+{
+ return clk_round_rate(clk_get_parent(hw->clk), rate);
+}
+
+static int wm831x_clkout_set_rate(struct clk_hw *hw, unsigned long rate,
+ unsigned long *parent_rate)
+{
+ *parent_rate = rate;
+ return CLK_SET_RATE_PROPAGATE;
+}
+
+static struct clk *wm831x_clkout_get_parent(struct clk_hw *hw)
+{
+ struct wm831x_clk *clkdata = container_of(hw, struct wm831x_clk,
+ clkout_hw);
+ struct wm831x *wm831x = clkdata->wm831x;
+ int ret;
+
+ ret = wm831x_reg_read(wm831x, WM831X_CLOCK_CONTROL_1);
+ if (ret < 0) {
+ dev_err(wm831x->dev, "Unable to read CLOCK_CONTROL_1: %d\n",
+ ret);
+ return NULL;
+ }
+
+ if (ret & WM831X_CLKOUT_SRC)
+ return clkdata->xtal_hw.clk;
+ else
+ return clkdata->fll_hw.clk;
+}
+
+static const struct clk_hw_ops wm831x_clkout_ops = {
+ .prepare = wm831x_clkout_prepare,
+ .unprepare = wm831x_clkout_unprepare,
+ .recalc_rate = wm831x_clkout_recalc_rate,
+ .round_rate = wm831x_clkout_round_rate,
+ .set_rate = wm831x_clkout_set_rate,
+ .get_parent = wm831x_clkout_get_parent,
+};
+
+static __devinit int wm831x_clk_probe(struct platform_device *pdev)
+{
+ struct wm831x *wm831x = dev_get_drvdata(pdev->dev.parent);
+ struct wm831x_clk *clkdata;
+ int ret;
+
+ clkdata = kzalloc(sizeof(*clkdata), GFP_KERNEL);
+ if (!clkdata)
+ return -ENOMEM;
+
+ /* XTAL_ENA can only be set via OTP/InstantConfig so just read once */
+ ret = wm831x_reg_read(wm831x, WM831X_CLOCK_CONTROL_2);
+ if (ret < 0) {
+ dev_err(wm831x->dev, "Unable to read CLOCK_CONTROL_2: %d\n",
+ ret);
+ goto err_alloc;
+ }
+ clkdata->xtal_ena = ret & WM831X_XTAL_ENA;
+
+ if (!clk_register(wm831x->dev, &wm831x_xtal_ops, &clkdata->xtal_hw,
+ "xtal")) {
+ ret = -EINVAL;
+ goto err_alloc;
+ }
+
+ if (!clk_register(wm831x->dev, &wm831x_fll_ops, &clkdata->fll_hw,
+ "fll")) {
+ ret = -EINVAL;
+ goto err_xtal;
+ }
+
+ if (!clk_register(wm831x->dev, &wm831x_clkout_ops, &clkdata->clkout_hw,
+ "clkout")) {
+ ret = -EINVAL;
+ goto err_fll;
+ }
+
+ dev_set_drvdata(&pdev->dev, clkdata);
+
+ return 0;
+
+err_fll:
+ clk_unregister(clkdata->fll_hw.clk);
+err_xtal:
+ clk_unregister(clkdata->xtal_hw.clk);
+err_alloc:
+ kfree(clkdata);
+ return ret;
+}
+
+static __devexit int wm831x_clk_remove(struct platform_device *pdev)
+{
+ struct wm831x_clk *clkdata = dev_get_drvdata(&pdev->dev);
+
+ clk_unregister(clkdata->clkout_hw.clk);
+ clk_unregister(clkdata->fll_hw.clk);
+ clk_unregister(clkdata->xtal_hw.clk);
+ kfree(clkdata);
+
+ return 0;
+}
+
+static struct platform_driver wm831x_clk_driver = {
+ .probe = wm831x_clk_probe,
+ .remove = __devexit_p(wm831x_clk_remove),
+ .driver = {
+ .name = "wm831x-clk",
+ .owner = THIS_MODULE,
+ },
+};
+
+static int __init wm831x_clk_init(void)
+{
+ int ret;
+
+ ret = platform_driver_register(&wm831x_clk_driver);
+ if (ret != 0)
+ pr_err("Failed to register WM831x clock driver: %d\n", ret);
+
+ return ret;
+}
+module_init(wm831x_clk_init);
+
+static void __exit wm831x_clk_exit(void)
+{
+ platform_driver_unregister(&wm831x_clk_driver);
+}
+module_exit(wm831x_clk_exit);
+
+/* Module information */
+MODULE_AUTHOR("Mark Brown <broonie@opensource.wolfsonmicro.com>");
+MODULE_DESCRIPTION("WM831x clock driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:wm831x-clk");
--
1.7.5.4