diff options
Diffstat (limited to 'drivers/clk/meson/clk-cpu.c')
| -rw-r--r-- | drivers/clk/meson/clk-cpu.c | 242 |
1 files changed, 242 insertions, 0 deletions
diff --git a/drivers/clk/meson/clk-cpu.c b/drivers/clk/meson/clk-cpu.c new file mode 100644 index 000000000000..71ad493b94df --- /dev/null +++ b/drivers/clk/meson/clk-cpu.c @@ -0,0 +1,242 @@ +/* + * Copyright (c) 2015 Endless Mobile, Inc. + * Author: Carlo Caione <carlo@endlessm.com> + * + * This program is free software; you can redistribute it and/or modify it + * under the terms and conditions of the GNU General Public License, + * version 2, as published by the Free Software Foundation. + * + * This program is distributed in the hope 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. + * + * You should have received a copy of the GNU General Public License along with + * this program. If not, see <http://www.gnu.org/licenses/>. + */ + +/* + * CPU clock path: + * + * +-[/N]-----|3| + * MUX2 +--[/3]-+----------|2| MUX1 + * [sys_pll]---|1| |--[/2]------------|1|-|1| + * | |---+------------------|0| | |----- [a5_clk] + * +--|0| | | + * [xtal]---+-------------------------------|0| + * + * + * + */ + +#include <linux/delay.h> +#include <linux/err.h> +#include <linux/io.h> +#include <linux/module.h> +#include <linux/of_address.h> +#include <linux/slab.h> +#include <linux/clk-provider.h> + +#define MESON_CPU_CLK_CNTL1 0x00 +#define MESON_CPU_CLK_CNTL 0x40 + +#define MESON_CPU_CLK_MUX1 BIT(7) +#define MESON_CPU_CLK_MUX2 BIT(0) + +#define MESON_N_WIDTH 9 +#define MESON_N_SHIFT 20 +#define MESON_SEL_WIDTH 2 +#define MESON_SEL_SHIFT 2 + +#include "clkc.h" + +struct meson_clk_cpu { + struct notifier_block clk_nb; + const struct clk_div_table *div_table; + struct clk_hw hw; + void __iomem *base; + u16 reg_off; +}; +#define to_meson_clk_cpu_hw(_hw) container_of(_hw, struct meson_clk_cpu, hw) +#define to_meson_clk_cpu_nb(_nb) container_of(_nb, struct meson_clk_cpu, clk_nb) + +static long meson_clk_cpu_round_rate(struct clk_hw *hw, unsigned long rate, + unsigned long *prate) +{ + struct meson_clk_cpu *clk_cpu = to_meson_clk_cpu_hw(hw); + + return divider_round_rate(hw, rate, prate, clk_cpu->div_table, + MESON_N_WIDTH, CLK_DIVIDER_ROUND_CLOSEST); +} + +static int meson_clk_cpu_set_rate(struct clk_hw *hw, unsigned long rate, + unsigned long parent_rate) +{ + struct meson_clk_cpu *clk_cpu = to_meson_clk_cpu_hw(hw); + unsigned int div, sel, N = 0; + u32 reg; + + div = DIV_ROUND_UP(parent_rate, rate); + + if (div <= 3) { + sel = div - 1; + } else { + sel = 3; + N = div / 2; + } + + reg = readl(clk_cpu->base + clk_cpu->reg_off + MESON_CPU_CLK_CNTL1); + reg = PARM_SET(MESON_N_WIDTH, MESON_N_SHIFT, reg, N); + writel(reg, clk_cpu->base + clk_cpu->reg_off + MESON_CPU_CLK_CNTL1); + + reg = readl(clk_cpu->base + clk_cpu->reg_off + MESON_CPU_CLK_CNTL); + reg = PARM_SET(MESON_SEL_WIDTH, MESON_SEL_SHIFT, reg, sel); + writel(reg, clk_cpu->base + clk_cpu->reg_off + MESON_CPU_CLK_CNTL); + + return 0; +} + +static unsigned long meson_clk_cpu_recalc_rate(struct clk_hw *hw, + unsigned long parent_rate) +{ + struct meson_clk_cpu *clk_cpu = to_meson_clk_cpu_hw(hw); + unsigned int N, sel; + unsigned int div = 1; + u32 reg; + + reg = readl(clk_cpu->base + clk_cpu->reg_off + MESON_CPU_CLK_CNTL1); + N = PARM_GET(MESON_N_WIDTH, MESON_N_SHIFT, reg); + + reg = readl(clk_cpu->base + clk_cpu->reg_off + MESON_CPU_CLK_CNTL); + sel = PARM_GET(MESON_SEL_WIDTH, MESON_SEL_SHIFT, reg); + + if (sel < 3) + div = sel + 1; + else + div = 2 * N; + + return parent_rate / div; +} + +static int meson_clk_cpu_pre_rate_change(struct meson_clk_cpu *clk_cpu, + struct clk_notifier_data *ndata) +{ + u32 cpu_clk_cntl; + + /* switch MUX1 to xtal */ + cpu_clk_cntl = readl(clk_cpu->base + clk_cpu->reg_off + + MESON_CPU_CLK_CNTL); + cpu_clk_cntl &= ~MESON_CPU_CLK_MUX1; + writel(cpu_clk_cntl, clk_cpu->base + clk_cpu->reg_off + + MESON_CPU_CLK_CNTL); + udelay(100); + + /* switch MUX2 to sys-pll */ + cpu_clk_cntl |= MESON_CPU_CLK_MUX2; + writel(cpu_clk_cntl, clk_cpu->base + clk_cpu->reg_off + + MESON_CPU_CLK_CNTL); + + return 0; +} + +static int meson_clk_cpu_post_rate_change(struct meson_clk_cpu *clk_cpu, + struct clk_notifier_data *ndata) +{ + u32 cpu_clk_cntl; + + /* switch MUX1 to divisors' output */ + cpu_clk_cntl = readl(clk_cpu->base + clk_cpu->reg_off + + MESON_CPU_CLK_CNTL); + cpu_clk_cntl |= MESON_CPU_CLK_MUX1; + writel(cpu_clk_cntl, clk_cpu->base + clk_cpu->reg_off + + MESON_CPU_CLK_CNTL); + udelay(100); + + return 0; +} + +/* + * This clock notifier is called when the frequency of the of the parent + * PLL clock is to be changed. We use the xtal input as temporary parent + * while the PLL frequency is stabilized. + */ +static int meson_clk_cpu_notifier_cb(struct notifier_block *nb, + unsigned long event, void *data) +{ + struct clk_notifier_data *ndata = data; + struct meson_clk_cpu *clk_cpu = to_meson_clk_cpu_nb(nb); + int ret = 0; + + if (event == PRE_RATE_CHANGE) + ret = meson_clk_cpu_pre_rate_change(clk_cpu, ndata); + else if (event == POST_RATE_CHANGE) + ret = meson_clk_cpu_post_rate_change(clk_cpu, ndata); + + return notifier_from_errno(ret); +} + +static const struct clk_ops meson_clk_cpu_ops = { + .recalc_rate = meson_clk_cpu_recalc_rate, + .round_rate = meson_clk_cpu_round_rate, + .set_rate = meson_clk_cpu_set_rate, +}; + +struct clk *meson_clk_register_cpu(const struct clk_conf *clk_conf, + void __iomem *reg_base, + spinlock_t *lock) +{ + struct clk *clk; + struct clk *pclk; + struct meson_clk_cpu *clk_cpu; + struct clk_init_data init; + int ret; + + clk_cpu = kzalloc(sizeof(*clk_cpu), GFP_KERNEL); + if (!clk_cpu) + return ERR_PTR(-ENOMEM); + + clk_cpu->base = reg_base; + clk_cpu->reg_off = clk_conf->reg_off; + clk_cpu->div_table = clk_conf->conf.div_table; + clk_cpu->clk_nb.notifier_call = meson_clk_cpu_notifier_cb; + + init.name = clk_conf->clk_name; + init.ops = &meson_clk_cpu_ops; + init.flags = clk_conf->flags | CLK_GET_RATE_NOCACHE; + init.flags |= CLK_SET_RATE_PARENT; + init.parent_names = clk_conf->clks_parent; + init.num_parents = 1; + + clk_cpu->hw.init = &init; + + pclk = __clk_lookup(clk_conf->clks_parent[0]); + if (!pclk) { + pr_err("%s: could not lookup parent clock %s\n", + __func__, clk_conf->clks_parent[0]); + ret = -EINVAL; + goto free_clk; + } + + ret = clk_notifier_register(pclk, &clk_cpu->clk_nb); + if (ret) { + pr_err("%s: failed to register clock notifier for %s\n", + __func__, clk_conf->clk_name); + goto free_clk; + } + + clk = clk_register(NULL, &clk_cpu->hw); + if (IS_ERR(clk)) { + ret = PTR_ERR(clk); + goto unregister_clk_nb; + } + + return clk; + +unregister_clk_nb: + clk_notifier_unregister(pclk, &clk_cpu->clk_nb); +free_clk: + kfree(clk_cpu); + + return ERR_PTR(ret); +} + |