diff options
Diffstat (limited to 'drivers/clk/clk-gate.c')
| -rw-r--r-- | drivers/clk/clk-gate.c | 164 |
1 files changed, 164 insertions, 0 deletions
diff --git a/drivers/clk/clk-gate.c b/drivers/clk/clk-gate.c new file mode 100644 index 00000000000..4a58c55255b --- /dev/null +++ b/drivers/clk/clk-gate.c @@ -0,0 +1,164 @@ +/* + * Copyright (C) 2010-2011 Canonical Ltd <jeremy.kerr@canonical.com> + * 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. + * + * Gated clock implementation + */ + +#include <linux/clk-provider.h> +#include <linux/module.h> +#include <linux/slab.h> +#include <linux/io.h> +#include <linux/err.h> +#include <linux/string.h> + +/** + * DOC: basic gatable clock which can gate and ungate it's ouput + * + * Traits of this clock: + * prepare - clk_(un)prepare only ensures parent is (un)prepared + * enable - clk_enable and clk_disable are functional & control gating + * rate - inherits rate from parent. No clk_set_rate support + * parent - fixed parent. No clk_set_parent support + */ + +#define to_clk_gate(_hw) container_of(_hw, struct clk_gate, hw) + +/* + * It works on following logic: + * + * For enabling clock, enable = 1 + * set2dis = 1 -> clear bit -> set = 0 + * set2dis = 0 -> set bit -> set = 1 + * + * For disabling clock, enable = 0 + * set2dis = 1 -> set bit -> set = 1 + * set2dis = 0 -> clear bit -> set = 0 + * + * So, result is always: enable xor set2dis. + */ +static void clk_gate_endisable(struct clk_hw *hw, int enable) +{ + struct clk_gate *gate = to_clk_gate(hw); + int set = gate->flags & CLK_GATE_SET_TO_DISABLE ? 1 : 0; + unsigned long flags = 0; + u32 reg; + + set ^= enable; + + if (gate->lock) + spin_lock_irqsave(gate->lock, flags); + + if (gate->flags & CLK_GATE_HIWORD_MASK) { + reg = BIT(gate->bit_idx + 16); + if (set) + reg |= BIT(gate->bit_idx); + } else { + reg = clk_readl(gate->reg); + + if (set) + reg |= BIT(gate->bit_idx); + else + reg &= ~BIT(gate->bit_idx); + } + + clk_writel(reg, gate->reg); + + if (gate->lock) + spin_unlock_irqrestore(gate->lock, flags); +} + +static int clk_gate_enable(struct clk_hw *hw) +{ + clk_gate_endisable(hw, 1); + + return 0; +} + +static void clk_gate_disable(struct clk_hw *hw) +{ + clk_gate_endisable(hw, 0); +} + +static int clk_gate_is_enabled(struct clk_hw *hw) +{ + u32 reg; + struct clk_gate *gate = to_clk_gate(hw); + + reg = clk_readl(gate->reg); + + /* if a set bit disables this clk, flip it before masking */ + if (gate->flags & CLK_GATE_SET_TO_DISABLE) + reg ^= BIT(gate->bit_idx); + + reg &= BIT(gate->bit_idx); + + return reg ? 1 : 0; +} + +const struct clk_ops clk_gate_ops = { + .enable = clk_gate_enable, + .disable = clk_gate_disable, + .is_enabled = clk_gate_is_enabled, +}; +EXPORT_SYMBOL_GPL(clk_gate_ops); + +/** + * clk_register_gate - register a gate clock with the clock framework + * @dev: device that is registering this clock + * @name: name of this clock + * @parent_name: name of this clock's parent + * @flags: framework-specific flags for this clock + * @reg: register address to control gating of this clock + * @bit_idx: which bit in the register controls gating of this clock + * @clk_gate_flags: gate-specific flags for this clock + * @lock: shared register lock for this clock + */ +struct clk *clk_register_gate(struct device *dev, const char *name, + const char *parent_name, unsigned long flags, + void __iomem *reg, u8 bit_idx, + u8 clk_gate_flags, spinlock_t *lock) +{ + struct clk_gate *gate; + struct clk *clk; + struct clk_init_data init; + + if (clk_gate_flags & CLK_GATE_HIWORD_MASK) { + if (bit_idx > 16) { + pr_err("gate bit exceeds LOWORD field\n"); + return ERR_PTR(-EINVAL); + } + } + + /* allocate the gate */ + gate = kzalloc(sizeof(struct clk_gate), GFP_KERNEL); + if (!gate) { + pr_err("%s: could not allocate gated clk\n", __func__); + return ERR_PTR(-ENOMEM); + } + + init.name = name; + init.ops = &clk_gate_ops; + init.flags = flags | CLK_IS_BASIC; + init.parent_names = (parent_name ? &parent_name: NULL); + init.num_parents = (parent_name ? 1 : 0); + + /* struct clk_gate assignments */ + gate->reg = reg; + gate->bit_idx = bit_idx; + gate->flags = clk_gate_flags; + gate->lock = lock; + gate->hw.init = &init; + + clk = clk_register(dev, &gate->hw); + + if (IS_ERR(clk)) + kfree(gate); + + return clk; +} +EXPORT_SYMBOL_GPL(clk_register_gate); |