diff options
Diffstat (limited to 'drivers/clk/sunxi/clk-sun9i-cpus.c')
| -rw-r--r-- | drivers/clk/sunxi/clk-sun9i-cpus.c | 242 |
1 files changed, 242 insertions, 0 deletions
diff --git a/drivers/clk/sunxi/clk-sun9i-cpus.c b/drivers/clk/sunxi/clk-sun9i-cpus.c new file mode 100644 index 000000000..01255d827 --- /dev/null +++ b/drivers/clk/sunxi/clk-sun9i-cpus.c @@ -0,0 +1,242 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2015 Chen-Yu Tsai + * + * Chen-Yu Tsai <wens@csie.org> + * + * Allwinner A80 CPUS clock driver + * + */ + +#include <linux/clk.h> +#include <linux/clk-provider.h> +#include <linux/io.h> +#include <linux/slab.h> +#include <linux/spinlock.h> +#include <linux/of.h> +#include <linux/of_address.h> + +static DEFINE_SPINLOCK(sun9i_a80_cpus_lock); + +/** + * sun9i_a80_cpus_clk_setup() - Setup function for a80 cpus composite clk + */ + +#define SUN9I_CPUS_MAX_PARENTS 4 +#define SUN9I_CPUS_MUX_PARENT_PLL4 3 +#define SUN9I_CPUS_MUX_SHIFT 16 +#define SUN9I_CPUS_MUX_MASK GENMASK(17, 16) +#define SUN9I_CPUS_MUX_GET_PARENT(reg) ((reg & SUN9I_CPUS_MUX_MASK) >> \ + SUN9I_CPUS_MUX_SHIFT) + +#define SUN9I_CPUS_DIV_SHIFT 4 +#define SUN9I_CPUS_DIV_MASK GENMASK(5, 4) +#define SUN9I_CPUS_DIV_GET(reg) ((reg & SUN9I_CPUS_DIV_MASK) >> \ + SUN9I_CPUS_DIV_SHIFT) +#define SUN9I_CPUS_DIV_SET(reg, div) ((reg & ~SUN9I_CPUS_DIV_MASK) | \ + (div << SUN9I_CPUS_DIV_SHIFT)) +#define SUN9I_CPUS_PLL4_DIV_SHIFT 8 +#define SUN9I_CPUS_PLL4_DIV_MASK GENMASK(12, 8) +#define SUN9I_CPUS_PLL4_DIV_GET(reg) ((reg & SUN9I_CPUS_PLL4_DIV_MASK) >> \ + SUN9I_CPUS_PLL4_DIV_SHIFT) +#define SUN9I_CPUS_PLL4_DIV_SET(reg, div) ((reg & ~SUN9I_CPUS_PLL4_DIV_MASK) | \ + (div << SUN9I_CPUS_PLL4_DIV_SHIFT)) + +struct sun9i_a80_cpus_clk { + struct clk_hw hw; + void __iomem *reg; +}; + +#define to_sun9i_a80_cpus_clk(_hw) container_of(_hw, struct sun9i_a80_cpus_clk, hw) + +static unsigned long sun9i_a80_cpus_clk_recalc_rate(struct clk_hw *hw, + unsigned long parent_rate) +{ + struct sun9i_a80_cpus_clk *cpus = to_sun9i_a80_cpus_clk(hw); + unsigned long rate; + u32 reg; + + /* Fetch the register value */ + reg = readl(cpus->reg); + + /* apply pre-divider first if parent is pll4 */ + if (SUN9I_CPUS_MUX_GET_PARENT(reg) == SUN9I_CPUS_MUX_PARENT_PLL4) + parent_rate /= SUN9I_CPUS_PLL4_DIV_GET(reg) + 1; + + /* clk divider */ + rate = parent_rate / (SUN9I_CPUS_DIV_GET(reg) + 1); + + return rate; +} + +static long sun9i_a80_cpus_clk_round(unsigned long rate, u8 *divp, u8 *pre_divp, + u8 parent, unsigned long parent_rate) +{ + u8 div, pre_div = 1; + + /* + * clock can only divide, so we will never be able to achieve + * frequencies higher than the parent frequency + */ + if (parent_rate && rate > parent_rate) + rate = parent_rate; + + div = DIV_ROUND_UP(parent_rate, rate); + + /* calculate pre-divider if parent is pll4 */ + if (parent == SUN9I_CPUS_MUX_PARENT_PLL4 && div > 4) { + /* pre-divider is 1 ~ 32 */ + if (div < 32) { + pre_div = div; + div = 1; + } else if (div < 64) { + pre_div = DIV_ROUND_UP(div, 2); + div = 2; + } else if (div < 96) { + pre_div = DIV_ROUND_UP(div, 3); + div = 3; + } else { + pre_div = DIV_ROUND_UP(div, 4); + div = 4; + } + } + + /* we were asked to pass back divider values */ + if (divp) { + *divp = div - 1; + *pre_divp = pre_div - 1; + } + + return parent_rate / pre_div / div; +} + +static int sun9i_a80_cpus_clk_determine_rate(struct clk_hw *clk, + struct clk_rate_request *req) +{ + struct clk_hw *parent, *best_parent = NULL; + int i, num_parents; + unsigned long parent_rate, best = 0, child_rate, best_child_rate = 0; + unsigned long rate = req->rate; + + /* find the parent that can help provide the fastest rate <= rate */ + num_parents = clk_hw_get_num_parents(clk); + for (i = 0; i < num_parents; i++) { + parent = clk_hw_get_parent_by_index(clk, i); + if (!parent) + continue; + if (clk_hw_get_flags(clk) & CLK_SET_RATE_PARENT) + parent_rate = clk_hw_round_rate(parent, rate); + else + parent_rate = clk_hw_get_rate(parent); + + child_rate = sun9i_a80_cpus_clk_round(rate, NULL, NULL, i, + parent_rate); + + if (child_rate <= rate && child_rate > best_child_rate) { + best_parent = parent; + best = parent_rate; + best_child_rate = child_rate; + } + } + + if (!best_parent) + return -EINVAL; + + req->best_parent_hw = best_parent; + req->best_parent_rate = best; + req->rate = best_child_rate; + + return 0; +} + +static int sun9i_a80_cpus_clk_set_rate(struct clk_hw *hw, unsigned long rate, + unsigned long parent_rate) +{ + struct sun9i_a80_cpus_clk *cpus = to_sun9i_a80_cpus_clk(hw); + unsigned long flags; + u8 div, pre_div, parent; + u32 reg; + + spin_lock_irqsave(&sun9i_a80_cpus_lock, flags); + + reg = readl(cpus->reg); + + /* need to know which parent is used to apply pre-divider */ + parent = SUN9I_CPUS_MUX_GET_PARENT(reg); + sun9i_a80_cpus_clk_round(rate, &div, &pre_div, parent, parent_rate); + + reg = SUN9I_CPUS_DIV_SET(reg, div); + reg = SUN9I_CPUS_PLL4_DIV_SET(reg, pre_div); + writel(reg, cpus->reg); + + spin_unlock_irqrestore(&sun9i_a80_cpus_lock, flags); + + return 0; +} + +static const struct clk_ops sun9i_a80_cpus_clk_ops = { + .determine_rate = sun9i_a80_cpus_clk_determine_rate, + .recalc_rate = sun9i_a80_cpus_clk_recalc_rate, + .set_rate = sun9i_a80_cpus_clk_set_rate, +}; + +static void sun9i_a80_cpus_setup(struct device_node *node) +{ + const char *clk_name = node->name; + const char *parents[SUN9I_CPUS_MAX_PARENTS]; + struct resource res; + struct sun9i_a80_cpus_clk *cpus; + struct clk_mux *mux; + struct clk *clk; + int ret; + + cpus = kzalloc(sizeof(*cpus), GFP_KERNEL); + if (!cpus) + return; + + cpus->reg = of_io_request_and_map(node, 0, of_node_full_name(node)); + if (IS_ERR(cpus->reg)) + goto err_free_cpus; + + of_property_read_string(node, "clock-output-names", &clk_name); + + /* we have a mux, we will have >1 parents */ + ret = of_clk_parent_fill(node, parents, SUN9I_CPUS_MAX_PARENTS); + + mux = kzalloc(sizeof(*mux), GFP_KERNEL); + if (!mux) + goto err_unmap; + + /* set up clock properties */ + mux->reg = cpus->reg; + mux->shift = SUN9I_CPUS_MUX_SHIFT; + /* un-shifted mask is what mux_clk expects */ + mux->mask = SUN9I_CPUS_MUX_MASK >> SUN9I_CPUS_MUX_SHIFT; + mux->lock = &sun9i_a80_cpus_lock; + + clk = clk_register_composite(NULL, clk_name, parents, ret, + &mux->hw, &clk_mux_ops, + &cpus->hw, &sun9i_a80_cpus_clk_ops, + NULL, NULL, 0); + if (IS_ERR(clk)) + goto err_free_mux; + + ret = of_clk_add_provider(node, of_clk_src_simple_get, clk); + if (ret) + goto err_unregister; + + return; + +err_unregister: + clk_unregister(clk); +err_free_mux: + kfree(mux); +err_unmap: + iounmap(cpus->reg); + of_address_to_resource(node, 0, &res); + release_mem_region(res.start, resource_size(&res)); +err_free_cpus: + kfree(cpus); +} +CLK_OF_DECLARE(sun9i_a80_cpus, "allwinner,sun9i-a80-cpus-clk", + sun9i_a80_cpus_setup); |