diff options
Diffstat (limited to 'drivers/clk/clk-mux.c')
| -rw-r--r-- | drivers/clk/clk-mux.c | 179 |
1 files changed, 179 insertions, 0 deletions
diff --git a/drivers/clk/clk-mux.c b/drivers/clk/clk-mux.c new file mode 100644 index 00000000000..4f96ff3ba72 --- /dev/null +++ b/drivers/clk/clk-mux.c @@ -0,0 +1,179 @@ +/* + * 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); + int num_parents = __clk_get_num_parents(hw->clk); + 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 = clk_readl(mux->reg) >> mux->shift; + val &= mux->mask; + + if (mux->table) { + int i; + + for (i = 0; i < num_parents; i++) + if (mux->table[i] == val) + return i; + return -EINVAL; + } + + if (val && (mux->flags & CLK_MUX_INDEX_BIT)) + val = ffs(val) - 1; + + if (val && (mux->flags & CLK_MUX_INDEX_ONE)) + val--; + + if (val >= num_parents) + return -EINVAL; + + return val; +} + +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->table) + index = mux->table[index]; + + else { + 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); + + if (mux->flags & CLK_MUX_HIWORD_MASK) { + val = mux->mask << (mux->shift + 16); + } else { + val = clk_readl(mux->reg); + val &= ~(mux->mask << mux->shift); + } + val |= index << mux->shift; + clk_writel(val, mux->reg); + + if (mux->lock) + spin_unlock_irqrestore(mux->lock, flags); + + return 0; +} + +const struct clk_ops clk_mux_ops = { + .get_parent = clk_mux_get_parent, + .set_parent = clk_mux_set_parent, + .determine_rate = __clk_mux_determine_rate, +}; +EXPORT_SYMBOL_GPL(clk_mux_ops); + +const struct clk_ops clk_mux_ro_ops = { + .get_parent = clk_mux_get_parent, +}; +EXPORT_SYMBOL_GPL(clk_mux_ro_ops); + +struct clk *clk_register_mux_table(struct device *dev, const char *name, + const char **parent_names, u8 num_parents, unsigned long flags, + void __iomem *reg, u8 shift, u32 mask, + u8 clk_mux_flags, u32 *table, spinlock_t *lock) +{ + struct clk_mux *mux; + struct clk *clk; + struct clk_init_data init; + u8 width = 0; + + if (clk_mux_flags & CLK_MUX_HIWORD_MASK) { + width = fls(mask) - ffs(mask) + 1; + if (width + shift > 16) { + pr_err("mux value exceeds LOWORD field\n"); + return ERR_PTR(-EINVAL); + } + } + + /* allocate the mux */ + mux = kzalloc(sizeof(struct clk_mux), GFP_KERNEL); + if (!mux) { + pr_err("%s: could not allocate mux clk\n", __func__); + return ERR_PTR(-ENOMEM); + } + + init.name = name; + if (clk_mux_flags & CLK_MUX_READ_ONLY) + init.ops = &clk_mux_ro_ops; + else + init.ops = &clk_mux_ops; + init.flags = flags | CLK_IS_BASIC; + init.parent_names = parent_names; + init.num_parents = num_parents; + + /* struct clk_mux assignments */ + mux->reg = reg; + mux->shift = shift; + mux->mask = mask; + mux->flags = clk_mux_flags; + mux->lock = lock; + mux->table = table; + mux->hw.init = &init; + + clk = clk_register(dev, &mux->hw); + + if (IS_ERR(clk)) + kfree(mux); + + return clk; +} +EXPORT_SYMBOL_GPL(clk_register_mux_table); + +struct clk *clk_register_mux(struct device *dev, const char *name, + const char **parent_names, u8 num_parents, unsigned long flags, + void __iomem *reg, u8 shift, u8 width, + u8 clk_mux_flags, spinlock_t *lock) +{ + u32 mask = BIT(width) - 1; + + return clk_register_mux_table(dev, name, parent_names, num_parents, + flags, reg, shift, mask, clk_mux_flags, + NULL, lock); +} +EXPORT_SYMBOL_GPL(clk_register_mux); |