diff options
Diffstat (limited to 'drivers/clk')
| -rw-r--r-- | drivers/clk/samsung/clk-cpu.c | 177 | ||||
| -rw-r--r-- | drivers/clk/samsung/clk-cpu.h | 4 |
2 files changed, 181 insertions, 0 deletions
diff --git a/drivers/clk/samsung/clk-cpu.c b/drivers/clk/samsung/clk-cpu.c index deb5e708f762..fbf4c4208e06 100644 --- a/drivers/clk/samsung/clk-cpu.c +++ b/drivers/clk/samsung/clk-cpu.c @@ -29,6 +29,7 @@ * down in order to keep the output clock rate within the previous OPP limits. */ +#include <linux/delay.h> #include <linux/errno.h> #include <linux/io.h> #include <linux/slab.h> @@ -51,6 +52,8 @@ typedef int (*exynos_rate_change_fn_t)(struct clk_notifier_data *ndata, * @div_cpu1: offset of CPU DIV1 register (for modifying divider values) * @div_stat_cpu0: offset of CPU DIV0_STAT register (for checking DIV status) * @div_stat_cpu1: offset of CPU DIV1_STAT register (for checking DIV status) + * @mux: offset of MUX register for choosing CPU clock source + * @divs: offsets of DIV registers (ACLK, ATCLK, PCLKDBG and PERIPHCLK) */ struct exynos_cpuclk_regs { u32 mux_sel; @@ -59,6 +62,9 @@ struct exynos_cpuclk_regs { u32 div_cpu1; u32 div_stat_cpu0; u32 div_stat_cpu1; + + u32 mux; + u32 divs[4]; }; /** @@ -397,6 +403,167 @@ static int exynos5433_cpuclk_post_rate_change(struct clk_notifier_data *ndata, return 0; } +/* ---- Exynos850 ----------------------------------------------------------- */ + +#define E850_DIV_RATIO_MASK GENMASK(3, 0) +#define E850_BUSY_MASK BIT(16) + +/* Max time for divider or mux to stabilize, usec */ +#define E850_DIV_MUX_STAB_TIME 100 +/* OSCCLK clock rate, Hz */ +#define E850_OSCCLK (26 * MHZ) + +static const struct exynos_cpuclk_regs e850cl0_cpuclk_regs = { + .mux = 0x100c, + .divs = { 0x1800, 0x1808, 0x180c, 0x1810 }, +}; + +static const struct exynos_cpuclk_regs e850cl1_cpuclk_regs = { + .mux = 0x1000, + .divs = { 0x1800, 0x1808, 0x180c, 0x1810 }, +}; + +/* + * Set alternate parent rate to "rate" value or less. + * + * rate: Desired alt_parent rate, or 0 for max alt_parent rate + * + * Exynos850 doesn't have CPU clock divider in CMU_CPUCLx block (CMUREF divider + * doesn't affect CPU speed). So CPUCLx_SWITCH divider from CMU_TOP is used + * instead to adjust alternate parent speed. + * + * It's possible to use clk_set_max_rate() instead of this function, but it + * would set overly pessimistic rate values to alternate parent. + */ +static int exynos850_alt_parent_set_max_rate(const struct clk_hw *alt_parent, + unsigned long rate) +{ + struct clk_hw *clk_div, *clk_divp; + unsigned long divp_rate, div_rate, div; + int ret; + + /* Divider from CMU_TOP */ + clk_div = clk_hw_get_parent(alt_parent); + if (!clk_div) + return -ENOENT; + /* Divider's parent from CMU_TOP */ + clk_divp = clk_hw_get_parent(clk_div); + if (!clk_divp) + return -ENOENT; + /* Divider input rate */ + divp_rate = clk_hw_get_rate(clk_divp); + if (!divp_rate) + return -EINVAL; + + /* Calculate new alt_parent rate for integer divider value */ + if (rate == 0) + div = 1; + else + div = DIV_ROUND_UP(divp_rate, rate); + div_rate = DIV_ROUND_UP(divp_rate, div); + WARN_ON(div >= MAX_DIV); + + /* alt_parent will propagate this change up to the divider */ + ret = clk_set_rate(alt_parent->clk, div_rate); + if (ret) + return ret; + udelay(E850_DIV_MUX_STAB_TIME); + + return 0; +} + +/* Handler for pre-rate change notification from parent clock */ +static int exynos850_cpuclk_pre_rate_change(struct clk_notifier_data *ndata, + struct exynos_cpuclk *cpuclk) +{ + const unsigned int shifts[4] = { 16, 12, 8, 4 }; /* E850_CPU_DIV0() */ + const struct exynos_cpuclk_regs * const regs = cpuclk->chip->regs; + const struct exynos_cpuclk_cfg_data *cfg_data = cpuclk->cfg; + const struct clk_hw *alt_parent = cpuclk->alt_parent; + void __iomem *base = cpuclk->base; + unsigned long alt_prate = clk_hw_get_rate(alt_parent); + unsigned long flags; + u32 mux_reg; + size_t i; + int ret; + + /* No actions are needed when switching to or from OSCCLK parent */ + if (ndata->new_rate == E850_OSCCLK || ndata->old_rate == E850_OSCCLK) + return 0; + + /* Find out the divider values to use for clock data */ + while ((cfg_data->prate * 1000) != ndata->new_rate) { + if (cfg_data->prate == 0) + return -EINVAL; + cfg_data++; + } + + /* + * 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_prate until the dividers are + * set. Also workaround the issue of the dividers being set to lower + * values before the parent clock speed is set to new lower speed + * (this can result in too high speed of armclk output clocks). + */ + if (alt_prate > ndata->old_rate || ndata->old_rate > ndata->new_rate) { + unsigned long tmp_rate = min(ndata->old_rate, ndata->new_rate); + + ret = exynos850_alt_parent_set_max_rate(alt_parent, tmp_rate); + if (ret) + return ret; + } + + spin_lock_irqsave(cpuclk->lock, flags); + + /* Select the alternate parent */ + mux_reg = readl(base + regs->mux); + writel(mux_reg | 1, base + regs->mux); + wait_until_mux_stable(base + regs->mux, 16, 1, 0); + + /* Alternate parent is active now. Set the dividers */ + for (i = 0; i < ARRAY_SIZE(shifts); ++i) { + unsigned long div = (cfg_data->div0 >> shifts[i]) & 0xf; + u32 val; + + val = readl(base + regs->divs[i]); + val = (val & ~E850_DIV_RATIO_MASK) | div; + writel(val, base + regs->divs[i]); + wait_until_divider_stable(base + regs->divs[i], E850_BUSY_MASK); + } + + spin_unlock_irqrestore(cpuclk->lock, flags); + + return 0; +} + +/* Handler for post-rate change notification from parent clock */ +static int exynos850_cpuclk_post_rate_change(struct clk_notifier_data *ndata, + struct exynos_cpuclk *cpuclk) +{ + const struct exynos_cpuclk_regs * const regs = cpuclk->chip->regs; + const struct clk_hw *alt_parent = cpuclk->alt_parent; + void __iomem *base = cpuclk->base; + unsigned long flags; + u32 mux_reg; + + /* No actions are needed when switching to or from OSCCLK parent */ + if (ndata->new_rate == E850_OSCCLK || ndata->old_rate == E850_OSCCLK) + return 0; + + spin_lock_irqsave(cpuclk->lock, flags); + + /* Select main parent (PLL) for mux */ + mux_reg = readl(base + regs->mux); + writel(mux_reg & ~1, base + regs->mux); + wait_until_mux_stable(base + regs->mux, 16, 1, 0); + + spin_unlock_irqrestore(cpuclk->lock, flags); + + /* Set alt_parent rate back to max */ + return exynos850_alt_parent_set_max_rate(alt_parent, 0); +} + /* -------------------------------------------------------------------------- */ /* Common round rate callback usable for all types of CPU clocks */ @@ -459,6 +626,16 @@ static const struct exynos_cpuclk_chip exynos_clkcpu_chips[] = { .pre_rate_cb = exynos5433_cpuclk_pre_rate_change, .post_rate_cb = exynos5433_cpuclk_post_rate_change, }, + [CPUCLK_LAYOUT_E850_CL0] = { + .regs = &e850cl0_cpuclk_regs, + .pre_rate_cb = exynos850_cpuclk_pre_rate_change, + .post_rate_cb = exynos850_cpuclk_post_rate_change, + }, + [CPUCLK_LAYOUT_E850_CL1] = { + .regs = &e850cl1_cpuclk_regs, + .pre_rate_cb = exynos850_cpuclk_pre_rate_change, + .post_rate_cb = exynos850_cpuclk_post_rate_change, + }, }; /* helper function to register a CPU clock */ diff --git a/drivers/clk/samsung/clk-cpu.h b/drivers/clk/samsung/clk-cpu.h index 4382ab005ad3..892843611b0a 100644 --- a/drivers/clk/samsung/clk-cpu.h +++ b/drivers/clk/samsung/clk-cpu.h @@ -17,10 +17,14 @@ * enum exynos_cpuclk_layout - CPU clock registers layout compatibility * @CPUCLK_LAYOUT_E4210: Exynos4210 compatible layout * @CPUCLK_LAYOUT_E5433: Exynos5433 compatible layout + * @CPUCLK_LAYOUT_E850_CL0: Exynos850 cluster 0 compatible layout + * @CPUCLK_LAYOUT_E850_CL1: Exynos850 cluster 1 compatible layout */ enum exynos_cpuclk_layout { CPUCLK_LAYOUT_E4210, CPUCLK_LAYOUT_E5433, + CPUCLK_LAYOUT_E850_CL0, + CPUCLK_LAYOUT_E850_CL1, }; /** |