| /* |
| * 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; |
| } |
| |
| 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; |
| } |
| |
| const 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 = kzalloc(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); |
| } |