diff options
Diffstat (limited to 'drivers/clk/versatile/clk-sp810.c')
| -rw-r--r-- | drivers/clk/versatile/clk-sp810.c | 188 |
1 files changed, 188 insertions, 0 deletions
diff --git a/drivers/clk/versatile/clk-sp810.c b/drivers/clk/versatile/clk-sp810.c new file mode 100644 index 00000000000..bf9b15a585e --- /dev/null +++ b/drivers/clk/versatile/clk-sp810.c @@ -0,0 +1,188 @@ +/* + * 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. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * Copyright (C) 2013 ARM Limited + */ + +#include <linux/amba/sp810.h> +#include <linux/clkdev.h> +#include <linux/clk-provider.h> +#include <linux/err.h> +#include <linux/of.h> +#include <linux/of_address.h> + +#define to_clk_sp810_timerclken(_hw) \ + container_of(_hw, struct clk_sp810_timerclken, hw) + +struct clk_sp810; + +struct clk_sp810_timerclken { + struct clk_hw hw; + struct clk *clk; + struct clk_sp810 *sp810; + int channel; +}; + +struct clk_sp810 { + struct device_node *node; + int refclk_index, timclk_index; + void __iomem *base; + spinlock_t lock; + struct clk_sp810_timerclken timerclken[4]; + struct clk *refclk; + struct clk *timclk; +}; + +static u8 clk_sp810_timerclken_get_parent(struct clk_hw *hw) +{ + struct clk_sp810_timerclken *timerclken = to_clk_sp810_timerclken(hw); + u32 val = readl(timerclken->sp810->base + SCCTRL); + + return !!(val & (1 << SCCTRL_TIMERENnSEL_SHIFT(timerclken->channel))); +} + +static int clk_sp810_timerclken_set_parent(struct clk_hw *hw, u8 index) +{ + struct clk_sp810_timerclken *timerclken = to_clk_sp810_timerclken(hw); + struct clk_sp810 *sp810 = timerclken->sp810; + u32 val, shift = SCCTRL_TIMERENnSEL_SHIFT(timerclken->channel); + unsigned long flags = 0; + + if (WARN_ON(index > 1)) + return -EINVAL; + + spin_lock_irqsave(&sp810->lock, flags); + + val = readl(sp810->base + SCCTRL); + val &= ~(1 << shift); + val |= index << shift; + writel(val, sp810->base + SCCTRL); + + spin_unlock_irqrestore(&sp810->lock, flags); + + return 0; +} + +/* + * FIXME - setting the parent every time .prepare is invoked is inefficient. + * This is better handled by a dedicated clock tree configuration mechanism at + * init-time. Revisit this later when such a mechanism exists + */ +static int clk_sp810_timerclken_prepare(struct clk_hw *hw) +{ + struct clk_sp810_timerclken *timerclken = to_clk_sp810_timerclken(hw); + struct clk_sp810 *sp810 = timerclken->sp810; + struct clk *old_parent = __clk_get_parent(hw->clk); + struct clk *new_parent; + + if (!sp810->refclk) + sp810->refclk = of_clk_get(sp810->node, sp810->refclk_index); + + if (!sp810->timclk) + sp810->timclk = of_clk_get(sp810->node, sp810->timclk_index); + + if (WARN_ON(IS_ERR(sp810->refclk) || IS_ERR(sp810->timclk))) + return -ENOENT; + + /* Select fastest parent */ + if (clk_get_rate(sp810->refclk) > clk_get_rate(sp810->timclk)) + new_parent = sp810->refclk; + else + new_parent = sp810->timclk; + + /* Switch the parent if necessary */ + if (old_parent != new_parent) { + clk_prepare(new_parent); + clk_set_parent(hw->clk, new_parent); + clk_unprepare(old_parent); + } + + return 0; +} + +static void clk_sp810_timerclken_unprepare(struct clk_hw *hw) +{ + struct clk_sp810_timerclken *timerclken = to_clk_sp810_timerclken(hw); + struct clk_sp810 *sp810 = timerclken->sp810; + + clk_put(sp810->timclk); + clk_put(sp810->refclk); +} + +static const struct clk_ops clk_sp810_timerclken_ops = { + .prepare = clk_sp810_timerclken_prepare, + .unprepare = clk_sp810_timerclken_unprepare, + .get_parent = clk_sp810_timerclken_get_parent, + .set_parent = clk_sp810_timerclken_set_parent, +}; + +struct clk *clk_sp810_timerclken_of_get(struct of_phandle_args *clkspec, + void *data) +{ + struct clk_sp810 *sp810 = data; + + if (WARN_ON(clkspec->args_count != 1 || clkspec->args[0] > + ARRAY_SIZE(sp810->timerclken))) + return NULL; + + return sp810->timerclken[clkspec->args[0]].clk; +} + +void __init clk_sp810_of_setup(struct device_node *node) +{ + struct clk_sp810 *sp810 = kzalloc(sizeof(*sp810), GFP_KERNEL); + const char *parent_names[2]; + char name[12]; + struct clk_init_data init; + int i; + + if (!sp810) { + pr_err("Failed to allocate memory for SP810!\n"); + return; + } + + sp810->refclk_index = of_property_match_string(node, "clock-names", + "refclk"); + parent_names[0] = of_clk_get_parent_name(node, sp810->refclk_index); + + sp810->timclk_index = of_property_match_string(node, "clock-names", + "timclk"); + parent_names[1] = of_clk_get_parent_name(node, sp810->timclk_index); + + if (parent_names[0] <= 0 || parent_names[1] <= 0) { + pr_warn("Failed to obtain parent clocks for SP810!\n"); + return; + } + + sp810->node = node; + sp810->base = of_iomap(node, 0); + spin_lock_init(&sp810->lock); + + init.name = name; + init.ops = &clk_sp810_timerclken_ops; + init.flags = CLK_IS_BASIC; + init.parent_names = parent_names; + init.num_parents = ARRAY_SIZE(parent_names); + + for (i = 0; i < ARRAY_SIZE(sp810->timerclken); i++) { + snprintf(name, ARRAY_SIZE(name), "timerclken%d", i); + + sp810->timerclken[i].sp810 = sp810; + sp810->timerclken[i].channel = i; + sp810->timerclken[i].hw.init = &init; + + sp810->timerclken[i].clk = clk_register(NULL, + &sp810->timerclken[i].hw); + WARN_ON(IS_ERR(sp810->timerclken[i].clk)); + } + + of_clk_add_provider(node, clk_sp810_timerclken_of_get, sp810); +} +CLK_OF_DECLARE(sp810, "arm,sp810", clk_sp810_of_setup); |