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 int num_parents = __clk_get_num_parents(hw->clk); 36 u32 val; 37 38 /* 39 * FIXME need a mux-specific flag to determine if val is bitwise or numeric 40 * e.g. sys_clkin_ck's clksel field is 3 bits wide, but ranges from 0x1 41 * to 0x7 (index starts at one) 42 * OTOH, pmd_trace_clk_mux_ck uses a separate bit for each clock, so 43 * val = 0x4 really means "bit 2, index starts at bit 0" 44 */ 45 val = readl(mux->reg) >> mux->shift; 46 val &= mux->mask; 47 48 if (mux->table) { 49 int i; 50 51 for (i = 0; i < num_parents; i++) 52 if (mux->table[i] == val) 53 return i; 54 return -EINVAL; 55 } 56 57 if (val && (mux->flags & CLK_MUX_INDEX_BIT)) 58 val = ffs(val) - 1; 59 60 if (val && (mux->flags & CLK_MUX_INDEX_ONE)) 61 val--; 62 63 if (val >= num_parents) 64 return -EINVAL; 65 66 return val; 67 } 68 69 static int clk_mux_set_parent(struct clk_hw *hw, u8 index) 70 { 71 struct clk_mux *mux = to_clk_mux(hw); 72 u32 val; 73 unsigned long flags = 0; 74 75 if (mux->table) 76 index = mux->table[index]; 77 78 else { 79 if (mux->flags & CLK_MUX_INDEX_BIT) 80 index = (1 << ffs(index)); 81 82 if (mux->flags & CLK_MUX_INDEX_ONE) 83 index++; 84 } 85 86 if (mux->lock) 87 spin_lock_irqsave(mux->lock, flags); 88 89 val = readl(mux->reg); 90 val &= ~(mux->mask << mux->shift); 91 val |= index << mux->shift; 92 writel(val, mux->reg); 93 94 if (mux->lock) 95 spin_unlock_irqrestore(mux->lock, flags); 96 97 return 0; 98 } 99 100 const struct clk_ops clk_mux_ops = { 101 .get_parent = clk_mux_get_parent, 102 .set_parent = clk_mux_set_parent, 103 }; 104 EXPORT_SYMBOL_GPL(clk_mux_ops); 105 106 struct clk *clk_register_mux_table(struct device *dev, const char *name, 107 const char **parent_names, u8 num_parents, unsigned long flags, 108 void __iomem *reg, u8 shift, u32 mask, 109 u8 clk_mux_flags, u32 *table, spinlock_t *lock) 110 { 111 struct clk_mux *mux; 112 struct clk *clk; 113 struct clk_init_data init; 114 115 /* allocate the mux */ 116 mux = kzalloc(sizeof(struct clk_mux), GFP_KERNEL); 117 if (!mux) { 118 pr_err("%s: could not allocate mux clk\n", __func__); 119 return ERR_PTR(-ENOMEM); 120 } 121 122 init.name = name; 123 init.ops = &clk_mux_ops; 124 init.flags = flags | CLK_IS_BASIC; 125 init.parent_names = parent_names; 126 init.num_parents = num_parents; 127 128 /* struct clk_mux assignments */ 129 mux->reg = reg; 130 mux->shift = shift; 131 mux->mask = mask; 132 mux->flags = clk_mux_flags; 133 mux->lock = lock; 134 mux->table = table; 135 mux->hw.init = &init; 136 137 clk = clk_register(dev, &mux->hw); 138 139 if (IS_ERR(clk)) 140 kfree(mux); 141 142 return clk; 143 } 144 145 struct clk *clk_register_mux(struct device *dev, const char *name, 146 const char **parent_names, u8 num_parents, unsigned long flags, 147 void __iomem *reg, u8 shift, u8 width, 148 u8 clk_mux_flags, spinlock_t *lock) 149 { 150 u32 mask = BIT(width) - 1; 151 152 return clk_register_mux_table(dev, name, parent_names, num_parents, 153 flags, reg, shift, mask, clk_mux_flags, 154 NULL, lock); 155 } 156