diff options
Diffstat (limited to 'drivers/clk/rockchip/clk-cpu.c')
-rw-r--r-- | drivers/clk/rockchip/clk-cpu.c | 329 |
1 files changed, 329 insertions, 0 deletions
diff --git a/drivers/clk/rockchip/clk-cpu.c b/drivers/clk/rockchip/clk-cpu.c new file mode 100644 index 000000000000..75c8c45ef728 --- /dev/null +++ b/drivers/clk/rockchip/clk-cpu.c @@ -0,0 +1,329 @@ +/* + * Copyright (c) 2014 MundoReader S.L. + * Author: Heiko Stuebner <heiko@sntech.de> + * + * based on clk/samsung/clk-cpu.c + * Copyright (c) 2014 Samsung Electronics Co., Ltd. + * Author: Thomas Abraham <thomas.ab@samsung.com> + * + * 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. + * + * A CPU clock is defined as a clock supplied to a CPU or a group of CPUs. + * The CPU clock is typically derived from a hierarchy of clock + * blocks which includes mux and divider blocks. There are a number of other + * auxiliary clocks supplied to the CPU domain such as the debug blocks and AXI + * clock for CPU domain. The rates of these auxiliary clocks are related to the + * CPU clock rate and this relation is usually specified in the hardware manual + * of the SoC or supplied after the SoC characterization. + * + * The below implementation of the CPU clock allows the rate changes of the CPU + * clock and the corresponding rate changes of the auxillary clocks of the CPU + * domain. The platform clock driver provides a clock register configuration + * for each configurable rate which is then used to program the clock hardware + * registers to acheive a fast co-oridinated rate change for all the CPU domain + * clocks. + * + * On a rate change request for the CPU clock, the rate change is propagated + * upto the PLL supplying the clock to the CPU domain clock blocks. While the + * CPU domain PLL is reconfigured, the CPU domain clocks are driven using an + * alternate clock source. If required, the alternate clock source is divided + * down in order to keep the output clock rate within the previous OPP limits. + */ + +#include <linux/of.h> +#include <linux/slab.h> +#include <linux/io.h> +#include <linux/clk-provider.h> +#include "clk.h" + +/** + * struct rockchip_cpuclk: information about clock supplied to a CPU core. + * @hw: handle between ccf and cpu clock. + * @alt_parent: alternate parent clock to use when switching the speed + * of the primary parent clock. + * @reg_base: base register for cpu-clock values. + * @clk_nb: clock notifier registered for changes in clock speed of the + * primary parent clock. + * @rate_count: number of rates in the rate_table + * @rate_table: pll-rates and their associated dividers + * @reg_data: cpu-specific register settings + * @lock: clock lock + */ +struct rockchip_cpuclk { + struct clk_hw hw; + + struct clk_mux cpu_mux; + const struct clk_ops *cpu_mux_ops; + + struct clk *alt_parent; + void __iomem *reg_base; + struct notifier_block clk_nb; + unsigned int rate_count; + struct rockchip_cpuclk_rate_table *rate_table; + const struct rockchip_cpuclk_reg_data *reg_data; + spinlock_t *lock; +}; + +#define to_rockchip_cpuclk_hw(hw) container_of(hw, struct rockchip_cpuclk, hw) +#define to_rockchip_cpuclk_nb(nb) \ + container_of(nb, struct rockchip_cpuclk, clk_nb) + +static const struct rockchip_cpuclk_rate_table *rockchip_get_cpuclk_settings( + struct rockchip_cpuclk *cpuclk, unsigned long rate) +{ + const struct rockchip_cpuclk_rate_table *rate_table = + cpuclk->rate_table; + int i; + + for (i = 0; i < cpuclk->rate_count; i++) { + if (rate == rate_table[i].prate) + return &rate_table[i]; + } + + return NULL; +} + +static unsigned long rockchip_cpuclk_recalc_rate(struct clk_hw *hw, + unsigned long parent_rate) +{ + struct rockchip_cpuclk *cpuclk = to_rockchip_cpuclk_hw(hw); + const struct rockchip_cpuclk_reg_data *reg_data = cpuclk->reg_data; + u32 clksel0 = readl_relaxed(cpuclk->reg_base + reg_data->core_reg); + + clksel0 >>= reg_data->div_core_shift; + clksel0 &= reg_data->div_core_mask; + return parent_rate / (clksel0 + 1); +} + +static const struct clk_ops rockchip_cpuclk_ops = { + .recalc_rate = rockchip_cpuclk_recalc_rate, +}; + +static void rockchip_cpuclk_set_dividers(struct rockchip_cpuclk *cpuclk, + const struct rockchip_cpuclk_rate_table *rate) +{ + int i; + + /* alternate parent is active now. set the dividers */ + for (i = 0; i < ARRAY_SIZE(rate->divs); i++) { + const struct rockchip_cpuclk_clksel *clksel = &rate->divs[i]; + + if (!clksel->reg) + continue; + + pr_debug("%s: setting reg 0x%x to 0x%x\n", + __func__, clksel->reg, clksel->val); + writel(clksel->val , cpuclk->reg_base + clksel->reg); + } +} + +static int rockchip_cpuclk_pre_rate_change(struct rockchip_cpuclk *cpuclk, + struct clk_notifier_data *ndata) +{ + const struct rockchip_cpuclk_reg_data *reg_data = cpuclk->reg_data; + unsigned long alt_prate, alt_div; + + alt_prate = clk_get_rate(cpuclk->alt_parent); + + spin_lock(cpuclk->lock); + + /* + * If the old parent clock speed is less than the clock speed + * of the alternate parent, then it should be ensured that at no point + * the armclk speed is more than the old_rate until the dividers are + * set. + */ + if (alt_prate > ndata->old_rate) { + /* calculate dividers */ + alt_div = DIV_ROUND_UP(alt_prate, ndata->old_rate) - 1; + if (alt_div > reg_data->div_core_mask) { + pr_warn("%s: limiting alt-divider %lu to %d\n", + __func__, alt_div, reg_data->div_core_mask); + alt_div = reg_data->div_core_mask; + } + + /* + * Change parents and add dividers in a single transaction. + * + * NOTE: we do this in a single transaction so we're never + * dividing the primary parent by the extra dividers that were + * needed for the alt. + */ + pr_debug("%s: setting div %lu as alt-rate %lu > old-rate %lu\n", + __func__, alt_div, alt_prate, ndata->old_rate); + + writel(HIWORD_UPDATE(alt_div, reg_data->div_core_mask, + reg_data->div_core_shift) | + HIWORD_UPDATE(1, 1, reg_data->mux_core_shift), + cpuclk->reg_base + reg_data->core_reg); + } else { + /* select alternate parent */ + writel(HIWORD_UPDATE(1, 1, reg_data->mux_core_shift), + cpuclk->reg_base + reg_data->core_reg); + } + + spin_unlock(cpuclk->lock); + return 0; +} + +static int rockchip_cpuclk_post_rate_change(struct rockchip_cpuclk *cpuclk, + struct clk_notifier_data *ndata) +{ + const struct rockchip_cpuclk_reg_data *reg_data = cpuclk->reg_data; + const struct rockchip_cpuclk_rate_table *rate; + + rate = rockchip_get_cpuclk_settings(cpuclk, ndata->new_rate); + if (!rate) { + pr_err("%s: Invalid rate : %lu for cpuclk\n", + __func__, ndata->new_rate); + return -EINVAL; + } + + spin_lock(cpuclk->lock); + + if (ndata->old_rate < ndata->new_rate) + rockchip_cpuclk_set_dividers(cpuclk, rate); + + /* + * post-rate change event, re-mux to primary parent and remove dividers. + * + * NOTE: we do this in a single transaction so we're never dividing the + * primary parent by the extra dividers that were needed for the alt. + */ + + writel(HIWORD_UPDATE(0, reg_data->div_core_mask, + reg_data->div_core_shift) | + HIWORD_UPDATE(0, 1, reg_data->mux_core_shift), + cpuclk->reg_base + reg_data->core_reg); + + if (ndata->old_rate > ndata->new_rate) + rockchip_cpuclk_set_dividers(cpuclk, rate); + + spin_unlock(cpuclk->lock); + return 0; +} + +/* + * This clock notifier is called when the frequency of the parent clock + * of cpuclk is to be changed. This notifier handles the setting up all + * the divider clocks, remux to temporary parent and handling the safe + * frequency levels when using temporary parent. + */ +static int rockchip_cpuclk_notifier_cb(struct notifier_block *nb, + unsigned long event, void *data) +{ + struct clk_notifier_data *ndata = data; + struct rockchip_cpuclk *cpuclk = to_rockchip_cpuclk_nb(nb); + int ret = 0; + + pr_debug("%s: event %lu, old_rate %lu, new_rate: %lu\n", + __func__, event, ndata->old_rate, ndata->new_rate); + if (event == PRE_RATE_CHANGE) + ret = rockchip_cpuclk_pre_rate_change(cpuclk, ndata); + else if (event == POST_RATE_CHANGE) + ret = rockchip_cpuclk_post_rate_change(cpuclk, ndata); + + return notifier_from_errno(ret); +} + +struct clk *rockchip_clk_register_cpuclk(const char *name, + const char **parent_names, u8 num_parents, + const struct rockchip_cpuclk_reg_data *reg_data, + const struct rockchip_cpuclk_rate_table *rates, + int nrates, void __iomem *reg_base, spinlock_t *lock) +{ + struct rockchip_cpuclk *cpuclk; + struct clk_init_data init; + struct clk *clk, *cclk; + int ret; + + if (num_parents != 2) { + pr_err("%s: needs two parent clocks\n", __func__); + return ERR_PTR(-EINVAL); + } + + cpuclk = kzalloc(sizeof(*cpuclk), GFP_KERNEL); + if (!cpuclk) + return ERR_PTR(-ENOMEM); + + init.name = name; + init.parent_names = &parent_names[0]; + init.num_parents = 1; + init.ops = &rockchip_cpuclk_ops; + + /* only allow rate changes when we have a rate table */ + init.flags = (nrates > 0) ? CLK_SET_RATE_PARENT : 0; + + /* disallow automatic parent changes by ccf */ + init.flags |= CLK_SET_RATE_NO_REPARENT; + + init.flags |= CLK_GET_RATE_NOCACHE; + + cpuclk->reg_base = reg_base; + cpuclk->lock = lock; + cpuclk->reg_data = reg_data; + cpuclk->clk_nb.notifier_call = rockchip_cpuclk_notifier_cb; + cpuclk->hw.init = &init; + + cpuclk->alt_parent = __clk_lookup(parent_names[1]); + if (!cpuclk->alt_parent) { + pr_err("%s: could not lookup alternate parent\n", + __func__); + ret = -EINVAL; + goto free_cpuclk; + } + + ret = clk_prepare_enable(cpuclk->alt_parent); + if (ret) { + pr_err("%s: could not enable alternate parent\n", + __func__); + goto free_cpuclk; + } + + clk = __clk_lookup(parent_names[0]); + if (!clk) { + pr_err("%s: could not lookup parent clock %s\n", + __func__, parent_names[0]); + ret = -EINVAL; + goto free_cpuclk; + } + + ret = clk_notifier_register(clk, &cpuclk->clk_nb); + if (ret) { + pr_err("%s: failed to register clock notifier for %s\n", + __func__, name); + goto free_cpuclk; + } + + if (nrates > 0) { + cpuclk->rate_count = nrates; + cpuclk->rate_table = kmemdup(rates, + sizeof(*rates) * nrates, + GFP_KERNEL); + if (!cpuclk->rate_table) { + pr_err("%s: could not allocate memory for cpuclk rates\n", + __func__); + ret = -ENOMEM; + goto unregister_notifier; + } + } + + cclk = clk_register(NULL, &cpuclk->hw); + if (IS_ERR(clk)) { + pr_err("%s: could not register cpuclk %s\n", __func__, name); + ret = PTR_ERR(clk); + goto free_rate_table; + } + + return cclk; + +free_rate_table: + kfree(cpuclk->rate_table); +unregister_notifier: + clk_notifier_unregister(clk, &cpuclk->clk_nb); +free_cpuclk: + kfree(cpuclk); + return ERR_PTR(ret); +} |