| Mike Turquette | 9d9f78e | 2012-03-15 23:11:20 -0700 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright (C) 2011 Sascha Hauer, Pengutronix <s.hauer@pengutronix.de> |
| 3 | * Copyright (C) 2011 Richard Zhao, Linaro <richard.zhao@linaro.org> |
| 4 | * Copyright (C) 2011-2012 Mike Turquette, Linaro Ltd <mturquette@linaro.org> |
| 5 | * |
| 6 | * This program is free software; you can redistribute it and/or modify |
| 7 | * it under the terms of the GNU General Public License version 2 as |
| 8 | * published by the Free Software Foundation. |
| 9 | * |
| 10 | * Simple multiplexer clock implementation |
| 11 | */ |
| 12 | |
| 13 | #include <linux/clk.h> |
| 14 | #include <linux/clk-provider.h> |
| 15 | #include <linux/module.h> |
| 16 | #include <linux/slab.h> |
| 17 | #include <linux/io.h> |
| 18 | #include <linux/err.h> |
| 19 | |
| 20 | /* |
| 21 | * DOC: basic adjustable multiplexer clock that cannot gate |
| 22 | * |
| 23 | * Traits of this clock: |
| 24 | * prepare - clk_prepare only ensures that parents are prepared |
| 25 | * enable - clk_enable only ensures that parents are enabled |
| 26 | * rate - rate is only affected by parent switching. No clk_set_rate support |
| 27 | * parent - parent is adjustable through clk_set_parent |
| 28 | */ |
| 29 | |
| 30 | #define to_clk_mux(_hw) container_of(_hw, struct clk_mux, hw) |
| 31 | |
| 32 | static u8 clk_mux_get_parent(struct clk_hw *hw) |
| 33 | { |
| 34 | struct clk_mux *mux = to_clk_mux(hw); |
| 35 | u32 val; |
| 36 | |
| 37 | /* |
| 38 | * FIXME need a mux-specific flag to determine if val is bitwise or numeric |
| 39 | * e.g. sys_clkin_ck's clksel field is 3 bits wide, but ranges from 0x1 |
| 40 | * to 0x7 (index starts at one) |
| 41 | * OTOH, pmd_trace_clk_mux_ck uses a separate bit for each clock, so |
| 42 | * val = 0x4 really means "bit 2, index starts at bit 0" |
| 43 | */ |
| 44 | val = readl(mux->reg) >> mux->shift; |
| 45 | val &= (1 << mux->width) - 1; |
| 46 | |
| 47 | if (val && (mux->flags & CLK_MUX_INDEX_BIT)) |
| 48 | val = ffs(val) - 1; |
| 49 | |
| 50 | if (val && (mux->flags & CLK_MUX_INDEX_ONE)) |
| 51 | val--; |
| 52 | |
| 53 | if (val >= __clk_get_num_parents(hw->clk)) |
| 54 | return -EINVAL; |
| 55 | |
| 56 | return val; |
| 57 | } |
| 58 | EXPORT_SYMBOL_GPL(clk_mux_get_parent); |
| 59 | |
| 60 | static int clk_mux_set_parent(struct clk_hw *hw, u8 index) |
| 61 | { |
| 62 | struct clk_mux *mux = to_clk_mux(hw); |
| 63 | u32 val; |
| 64 | unsigned long flags = 0; |
| 65 | |
| 66 | if (mux->flags & CLK_MUX_INDEX_BIT) |
| 67 | index = (1 << ffs(index)); |
| 68 | |
| 69 | if (mux->flags & CLK_MUX_INDEX_ONE) |
| 70 | index++; |
| 71 | |
| 72 | if (mux->lock) |
| 73 | spin_lock_irqsave(mux->lock, flags); |
| 74 | |
| 75 | val = readl(mux->reg); |
| 76 | val &= ~(((1 << mux->width) - 1) << mux->shift); |
| 77 | val |= index << mux->shift; |
| 78 | writel(val, mux->reg); |
| 79 | |
| 80 | if (mux->lock) |
| 81 | spin_unlock_irqrestore(mux->lock, flags); |
| 82 | |
| 83 | return 0; |
| 84 | } |
| 85 | EXPORT_SYMBOL_GPL(clk_mux_set_parent); |
| 86 | |
| 87 | struct clk_ops clk_mux_ops = { |
| 88 | .get_parent = clk_mux_get_parent, |
| 89 | .set_parent = clk_mux_set_parent, |
| 90 | }; |
| 91 | EXPORT_SYMBOL_GPL(clk_mux_ops); |
| 92 | |
| 93 | struct clk *clk_register_mux(struct device *dev, const char *name, |
| 94 | char **parent_names, u8 num_parents, unsigned long flags, |
| 95 | void __iomem *reg, u8 shift, u8 width, |
| 96 | u8 clk_mux_flags, spinlock_t *lock) |
| 97 | { |
| 98 | struct clk_mux *mux; |
| 99 | |
| 100 | mux = kmalloc(sizeof(struct clk_mux), GFP_KERNEL); |
| 101 | |
| 102 | if (!mux) { |
| 103 | pr_err("%s: could not allocate mux clk\n", __func__); |
| 104 | return ERR_PTR(-ENOMEM); |
| 105 | } |
| 106 | |
| 107 | /* struct clk_mux assignments */ |
| 108 | mux->reg = reg; |
| 109 | mux->shift = shift; |
| 110 | mux->width = width; |
| 111 | mux->flags = clk_mux_flags; |
| 112 | mux->lock = lock; |
| 113 | |
| 114 | return clk_register(dev, name, &clk_mux_ops, &mux->hw, |
| 115 | parent_names, num_parents, flags); |
| 116 | } |