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authorSascha Hauer <s.hauer@pengutronix.de>2012-05-03 15:36:14 +0530
committerMike Turquette <mturquette@linaro.org>2012-05-08 14:13:25 -0700
commitf0948f59dbc8e725a96ba16da666e8f5cdd43ba8 (patch)
tree9343cecfdb735b4b9c327edea65e71801b5c3efe /drivers/clk/clk-fixed-factor.c
parent31df9db99549cd29bbe5e32da4492970e6f97191 (diff)
downloadlinux-f0948f59dbc8e725a96ba16da666e8f5cdd43ba8.tar.gz
clk: add a fixed factor clock
Having fixed factors/dividers in hardware is a common pattern, so add a basic clock type doing this. It basically describes a fixed factor clock using a nominator and a denominator. Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de> Reviewed-by: Viresh Kumar <viresh.kumar@st.com> Tested-by: Shawn Guo <shawn.guo@linaro.org> [mturquette@linaro.org: constify parent_names in static init macro] [mturquette@linaro.org: copy/paste bug from mux in static init macro] [mturquette@linaro.org: fix error handling in clk_register_fixed_factor] [mturquette@linaro.org: improve division accuracy; thanks to Saravana] Signed-off-by: Mike Turquette <mturquette@linaro.org>
Diffstat (limited to 'drivers/clk/clk-fixed-factor.c')
-rw-r--r--drivers/clk/clk-fixed-factor.c95
1 files changed, 95 insertions, 0 deletions
diff --git a/drivers/clk/clk-fixed-factor.c b/drivers/clk/clk-fixed-factor.c
new file mode 100644
index 00000000000..c8c003e217a
--- /dev/null
+++ b/drivers/clk/clk-fixed-factor.c
@@ -0,0 +1,95 @@
+/*
+ * Copyright (C) 2011 Sascha Hauer, Pengutronix <s.hauer@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>
+
+/*
+ * DOC: basic fixed multiplier and divider clock that cannot gate
+ *
+ * Traits of this clock:
+ * prepare - clk_prepare only ensures that parents are prepared
+ * enable - clk_enable only ensures that parents are enabled
+ * rate - rate is fixed. clk->rate = parent->rate / div * mult
+ * parent - fixed parent. No clk_set_parent support
+ */
+
+#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->mult / fix->div;
+}
+
+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 (__clk_get_flags(hw->clk) & CLK_SET_RATE_PARENT) {
+ 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;
+}
+
+static int clk_factor_set_rate(struct clk_hw *hw, unsigned long rate,
+ unsigned long parent_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_init_data init;
+ struct clk *clk;
+
+ fix = kmalloc(sizeof(*fix), GFP_KERNEL);
+ if (!fix) {
+ pr_err("%s: could not allocate fixed factor clk\n", __func__);
+ return ERR_PTR(-ENOMEM);
+ }
+
+ /* struct clk_fixed_factor assignments */
+ fix->mult = mult;
+ fix->div = div;
+ fix->hw.init = &init;
+
+ init.name = name;
+ init.ops = &clk_fixed_factor_ops;
+ init.flags = flags;
+ init.parent_names = &parent_name;
+ init.num_parents = 1;
+
+ clk = clk_register(dev, &fix->hw);
+
+ if (IS_ERR(clk))
+ kfree(fix);
+
+ return clk;
+}