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authorMike Turquette <mturquette@linaro.org>2012-03-16 10:11:20 +0400
committerArnd Bergmann <arnd@arndb.de>2012-03-17 00:35:02 +0400
commit9d9f78ed9af0e465d2fd15550471956e7f559b9f (patch)
tree8a65fc0844a35c928162f65b671a8a5786ea03ee /drivers/clk/clk-mux.c
parentb2476490ef11134b65544d8f062cff96c53e941b (diff)
downloadlinux-9d9f78ed9af0e465d2fd15550471956e7f559b9f.tar.xz
clk: basic clock hardware types
Many platforms support simple gateable clocks, fixed-rate clocks, adjustable divider clocks and multi-parent multiplexer clocks. This patch introduces basic clock types for the above-mentioned hardware which share some common characteristics. Based on original work by Jeremy Kerr and contribution by Jamie Iles. Dividers and multiplexor clocks originally contributed by Richard Zhao & Sascha Hauer. Signed-off-by: Mike Turquette <mturquette@linaro.org> Signed-off-by: Mike Turquette <mturquette@ti.com> Reviewed-by: Andrew Lunn <andrew@lunn.ch> Tested-by: Andrew Lunn <andrew@lunn.ch> Reviewed-by: Rob Herring <rob.herring@calxeda.com> Cc: Russell King <linux@arm.linux.org.uk> Cc: Jeremy Kerr <jeremy.kerr@canonical.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Arnd Bergman <arnd.bergmann@linaro.org> Cc: Paul Walmsley <paul@pwsan.com> Cc: Shawn Guo <shawn.guo@freescale.com> Cc: Sascha Hauer <s.hauer@pengutronix.de> Cc: Jamie Iles <jamie@jamieiles.com> Cc: Richard Zhao <richard.zhao@linaro.org> Cc: Saravana Kannan <skannan@codeaurora.org> Cc: Magnus Damm <magnus.damm@gmail.com> Cc: Mark Brown <broonie@opensource.wolfsonmicro.com> Cc: Linus Walleij <linus.walleij@stericsson.com> Cc: Stephen Boyd <sboyd@codeaurora.org> Cc: Amit Kucheria <amit.kucheria@linaro.org> Cc: Deepak Saxena <dsaxena@linaro.org> Cc: Grant Likely <grant.likely@secretlab.ca> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Diffstat (limited to 'drivers/clk/clk-mux.c')
-rw-r--r--drivers/clk/clk-mux.c116
1 files changed, 116 insertions, 0 deletions
diff --git a/drivers/clk/clk-mux.c b/drivers/clk/clk-mux.c
new file mode 100644
index 000000000000..c71ad1f41a97
--- /dev/null
+++ b/drivers/clk/clk-mux.c
@@ -0,0 +1,116 @@
+/*
+ * Copyright (C) 2011 Sascha Hauer, Pengutronix <s.hauer@pengutronix.de>
+ * Copyright (C) 2011 Richard Zhao, Linaro <richard.zhao@linaro.org>
+ * Copyright (C) 2011-2012 Mike Turquette, Linaro Ltd <mturquette@linaro.org>
+ *
+ * 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.
+ *
+ * Simple multiplexer clock implementation
+ */
+
+#include <linux/clk.h>
+#include <linux/clk-provider.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/io.h>
+#include <linux/err.h>
+
+/*
+ * DOC: basic adjustable multiplexer 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 only affected by parent switching. No clk_set_rate support
+ * parent - parent is adjustable through clk_set_parent
+ */
+
+#define to_clk_mux(_hw) container_of(_hw, struct clk_mux, hw)
+
+static u8 clk_mux_get_parent(struct clk_hw *hw)
+{
+ struct clk_mux *mux = to_clk_mux(hw);
+ u32 val;
+
+ /*
+ * FIXME need a mux-specific flag to determine if val is bitwise or numeric
+ * e.g. sys_clkin_ck's clksel field is 3 bits wide, but ranges from 0x1
+ * to 0x7 (index starts at one)
+ * OTOH, pmd_trace_clk_mux_ck uses a separate bit for each clock, so
+ * val = 0x4 really means "bit 2, index starts at bit 0"
+ */
+ val = readl(mux->reg) >> mux->shift;
+ val &= (1 << mux->width) - 1;
+
+ if (val && (mux->flags & CLK_MUX_INDEX_BIT))
+ val = ffs(val) - 1;
+
+ if (val && (mux->flags & CLK_MUX_INDEX_ONE))
+ val--;
+
+ if (val >= __clk_get_num_parents(hw->clk))
+ return -EINVAL;
+
+ return val;
+}
+EXPORT_SYMBOL_GPL(clk_mux_get_parent);
+
+static int clk_mux_set_parent(struct clk_hw *hw, u8 index)
+{
+ struct clk_mux *mux = to_clk_mux(hw);
+ u32 val;
+ unsigned long flags = 0;
+
+ if (mux->flags & CLK_MUX_INDEX_BIT)
+ index = (1 << ffs(index));
+
+ if (mux->flags & CLK_MUX_INDEX_ONE)
+ index++;
+
+ if (mux->lock)
+ spin_lock_irqsave(mux->lock, flags);
+
+ val = readl(mux->reg);
+ val &= ~(((1 << mux->width) - 1) << mux->shift);
+ val |= index << mux->shift;
+ writel(val, mux->reg);
+
+ if (mux->lock)
+ spin_unlock_irqrestore(mux->lock, flags);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(clk_mux_set_parent);
+
+struct clk_ops clk_mux_ops = {
+ .get_parent = clk_mux_get_parent,
+ .set_parent = clk_mux_set_parent,
+};
+EXPORT_SYMBOL_GPL(clk_mux_ops);
+
+struct clk *clk_register_mux(struct device *dev, const char *name,
+ char **parent_names, u8 num_parents, unsigned long flags,
+ void __iomem *reg, u8 shift, u8 width,
+ u8 clk_mux_flags, spinlock_t *lock)
+{
+ struct clk_mux *mux;
+
+ mux = kmalloc(sizeof(struct clk_mux), GFP_KERNEL);
+
+ if (!mux) {
+ pr_err("%s: could not allocate mux clk\n", __func__);
+ return ERR_PTR(-ENOMEM);
+ }
+
+ /* struct clk_mux assignments */
+ mux->reg = reg;
+ mux->shift = shift;
+ mux->width = width;
+ mux->flags = clk_mux_flags;
+ mux->lock = lock;
+
+ return clk_register(dev, name, &clk_mux_ops, &mux->hw,
+ parent_names, num_parents, flags);
+}