[RFC/PATCH 4/4] pxa: convert to common clock framework
Sascha Hauer
s.hauer at pengutronix.de
Sat Mar 17 12:07:44 EDT 2012
On Sat, Mar 17, 2012 at 11:24:25AM +0100, Philipp Zabel wrote:
> Hi Mike,
>
> On Fri, Mar 16, 2012 at 11:03 PM, Turquette, Mike <mturquette at ti.com> wrote:
> > On Fri, Mar 16, 2012 at 10:38 AM, Philipp Zabel <philipp.zabel at gmail.com> wrote:
> >> #define DEFINE_CK(_name, _cken, _ops) \
> >> -struct clk clk_##_name = { \
> >> - .ops = _ops, \
> >> + struct clk clk_##_name; \
> >> + static struct clk_pxa clk_pxa_##_name = { \
> >> + .hw = { \
> >> + .clk = &clk_##_name, \
> >> + }, \
> >> .cken = CKEN_##_cken, \
> >> + }; \
> >> + static struct clk clk_##_name = { \
> >> + .name = #_name, \
> >> + .ops = _ops, \
> >> + .hw = &clk_pxa_##_name.hw, \
> >> }
> >
> > Hi Philipp,
> >
> > It looks like your macros do not initialize the .parent_names,
> > .num_parents or .flags members of struct clk. __clk_init expects
> > those to be initialized before being called. The kerneldoc for
> > __clk_init states this:
> > http://git.linaro.org/gitweb?p=people/mturquette/linux.git;a=blob;f=include/linux/clk-private.h;h=e2cce6fa604686ea3bca0496998322bacaed854d;hb=c5836d8acd9846ec1675b269d994d96a8ee44df4#l49
>
> Yes, thank you! That was the problem.
>
> > You can use the macros for the basic clocks types as templates. The
> > gate and mux macros are good to look at since those show how to handle
> > a single-parent and multi-parent clock, respectively:
> > http://git.linaro.org/gitweb?p=people/mturquette/linux.git;a=blob;f=include/linux/clk-private.h;h=5e4312b6f5ccb1072273ce94e235874c74dd852d;hb=2508b44cd5c134691dc5d679f728bbf82af2abe0#l83
> > and
> > http://git.linaro.org/gitweb?p=people/mturquette/linux.git;a=blob;f=include/linux/clk-private.h;h=5e4312b6f5ccb1072273ce94e235874c74dd852d;hb=2508b44cd5c134691dc5d679f728bbf82af2abe0#l148
>
> If there was a fixed fractional divider clk element, a lot of the
> peripheral clocks could be derived from a fixed clk representing the
> 312 MHz PPLL on PXA27x (fixed -> divider -> gate), using just the
> basic clock templates.
You could try the following. It is not thoroughly tested but may be a
starting point. I need this aswell for i.MX so I will continue to work
on it soon.
Sascha
8<-------------------------------------------------------
clk: add a fixed factor clock
Having fixed factors/dividers in hardware is a common pattern, so
add a clock doing this. Currently no rate propagation is supported.
Signed-off-by: Sascha Hauer <s.hauer at pengutronix.de>
---
drivers/clk/Makefile | 2 +-
drivers/clk/clk-fixed-factor.c | 97 ++++++++++++++++++++++++++++++++++++++++
include/linux/clk-provider.h | 4 ++
3 files changed, 102 insertions(+), 1 deletions(-)
create mode 100644 drivers/clk/clk-fixed-factor.c
diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
index ba9a779..54f6f5b 100644
--- a/drivers/clk/Makefile
+++ b/drivers/clk/Makefile
@@ -1,4 +1,4 @@
obj-$(CONFIG_CLKDEV_LOOKUP) += clkdev.o
obj-$(CONFIG_COMMON_CLK) += clk.o clk-fixed-rate.o clk-gate.o \
- clk-mux.o clk-divider.o clk-test.o
+ clk-mux.o clk-divider.o clk-fixed-factor.o clk-test.o
diff --git a/drivers/clk/clk-fixed-factor.c b/drivers/clk/clk-fixed-factor.c
new file mode 100644
index 0000000..7c5e1fc
--- /dev/null
+++ b/drivers/clk/clk-fixed-factor.c
@@ -0,0 +1,97 @@
+/*
+ * Copyright (C) 2011 Sascha Hauer, Pengutronix <s.hauer at pengutronix.de>
+ *
+ * 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.
+ *
+ * Standard functionality for the common clock API.
+ */
+#include <linux/module.h>
+#include <linux/clk-provider.h>
+#include <linux/slab.h>
+#include <linux/err.h>
+
+struct clk_fixed_factor {
+ struct clk_hw hw;
+ unsigned int mult;
+ unsigned int div;
+ char *parent[1];
+};
+
+#define to_clk_fixed_factor(_hw) container_of(_hw, struct clk_fixed_factor, hw)
+
+static unsigned long clk_factor_recalc_rate(struct clk_hw *hw,
+ unsigned long parent_rate)
+{
+ struct clk_fixed_factor *fix = to_clk_fixed_factor(hw);
+
+ return (parent_rate / fix->div) * fix->mult;
+}
+
+static long clk_factor_round_rate(struct clk_hw *hw, unsigned long rate,
+ unsigned long *prate)
+{
+ struct clk_fixed_factor *fix = to_clk_fixed_factor(hw);
+
+ if (prate) {
+ unsigned long best_parent;
+ best_parent = (rate / fix->mult) * fix->div;
+ *prate = __clk_round_rate(__clk_get_parent(hw->clk),
+ best_parent);
+ return (*prate / fix->div) * fix->mult;
+ } else {
+ return (__clk_get_rate(__clk_get_parent(hw->clk)) / fix->div) * fix->mult;
+ }
+}
+
+static int clk_factor_set_rate(struct clk_hw *hw, unsigned long rate)
+{
+ return 0;
+}
+
+struct clk_ops clk_fixed_factor_ops = {
+ .round_rate = clk_factor_round_rate,
+ .set_rate = clk_factor_set_rate,
+ .recalc_rate = clk_factor_recalc_rate,
+};
+EXPORT_SYMBOL_GPL(clk_fixed_factor_ops);
+
+struct clk *clk_register_fixed_factor(struct device *dev, const char *name,
+ const char *parent_name, unsigned long flags,
+ unsigned int mult, unsigned int div)
+{
+ struct clk_fixed_factor *fix;
+ struct clk *clk;
+
+ fix = kmalloc(sizeof(struct clk_gate), GFP_KERNEL);
+
+ if (!fix) {
+ pr_err("%s: could not allocate gated clk\n", __func__);
+ return ERR_PTR(-ENOMEM);
+ }
+
+ /* struct clk_gate assignments */
+ fix->mult = mult;
+ fix->div = div;
+
+ if (parent_name) {
+ fix->parent[0] = kstrdup(parent_name, GFP_KERNEL);
+ if (!fix->parent[0])
+ goto out;
+ }
+
+ clk = clk_register(dev, name,
+ &clk_fixed_factor_ops, &fix->hw,
+ fix->parent,
+ (parent_name ? 1 : 0),
+ flags);
+ if (clk)
+ return clk;
+
+out:
+ kfree(fix->parent[0]);
+ kfree(fix);
+
+ return NULL;
+}
diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
index 5508897..21ca2f8 100644
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -257,6 +257,10 @@ struct clk *clk_register_mux(struct device *dev, const char *name,
void __iomem *reg, u8 shift, u8 width,
u8 clk_mux_flags, spinlock_t *lock);
+struct clk *clk_register_fixed_factor(struct device *dev, const char *name,
+ const char *parent_name, unsigned long flags,
+ unsigned int mult, unsigned int div);
+
/**
* clk_register - allocate a new clock, register it and return an opaque cookie
* @dev: device that is registering this clock
--
1.7.9.1
--
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