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Diffstat (limited to '')
| -rw-r--r-- | drivers/clk/sunxi-ng/ccu_sdm.c | 158 |
1 files changed, 158 insertions, 0 deletions
diff --git a/drivers/clk/sunxi-ng/ccu_sdm.c b/drivers/clk/sunxi-ng/ccu_sdm.c new file mode 100644 index 000000000..3b3dc9bdf --- /dev/null +++ b/drivers/clk/sunxi-ng/ccu_sdm.c @@ -0,0 +1,158 @@ +/* + * Copyright (C) 2017 Chen-Yu Tsai <wens@csie.org> + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as + * published by the Free Software Foundation; either version 2 of + * the License, or (at your option) any later version. + */ + +#include <linux/clk-provider.h> +#include <linux/spinlock.h> + +#include "ccu_sdm.h" + +bool ccu_sdm_helper_is_enabled(struct ccu_common *common, + struct ccu_sdm_internal *sdm) +{ + if (!(common->features & CCU_FEATURE_SIGMA_DELTA_MOD)) + return false; + + if (sdm->enable && !(readl(common->base + common->reg) & sdm->enable)) + return false; + + return !!(readl(common->base + sdm->tuning_reg) & sdm->tuning_enable); +} + +void ccu_sdm_helper_enable(struct ccu_common *common, + struct ccu_sdm_internal *sdm, + unsigned long rate) +{ + unsigned long flags; + unsigned int i; + u32 reg; + + if (!(common->features & CCU_FEATURE_SIGMA_DELTA_MOD)) + return; + + /* Set the pattern */ + for (i = 0; i < sdm->table_size; i++) + if (sdm->table[i].rate == rate) + writel(sdm->table[i].pattern, + common->base + sdm->tuning_reg); + + /* Make sure SDM is enabled */ + spin_lock_irqsave(common->lock, flags); + reg = readl(common->base + sdm->tuning_reg); + writel(reg | sdm->tuning_enable, common->base + sdm->tuning_reg); + spin_unlock_irqrestore(common->lock, flags); + + spin_lock_irqsave(common->lock, flags); + reg = readl(common->base + common->reg); + writel(reg | sdm->enable, common->base + common->reg); + spin_unlock_irqrestore(common->lock, flags); +} + +void ccu_sdm_helper_disable(struct ccu_common *common, + struct ccu_sdm_internal *sdm) +{ + unsigned long flags; + u32 reg; + + if (!(common->features & CCU_FEATURE_SIGMA_DELTA_MOD)) + return; + + spin_lock_irqsave(common->lock, flags); + reg = readl(common->base + common->reg); + writel(reg & ~sdm->enable, common->base + common->reg); + spin_unlock_irqrestore(common->lock, flags); + + spin_lock_irqsave(common->lock, flags); + reg = readl(common->base + sdm->tuning_reg); + writel(reg & ~sdm->tuning_enable, common->base + sdm->tuning_reg); + spin_unlock_irqrestore(common->lock, flags); +} + +/* + * Sigma delta modulation provides a way to do fractional-N frequency + * synthesis, in essence allowing the PLL to output any frequency + * within its operational range. On earlier SoCs such as the A10/A20, + * some PLLs support this. On later SoCs, all PLLs support this. + * + * The datasheets do not explain what the "wave top" and "wave bottom" + * parameters mean or do, nor how to calculate the effective output + * frequency. The only examples (and real world usage) are for the audio + * PLL to generate 24.576 and 22.5792 MHz clock rates used by the audio + * peripherals. The author lacks the underlying domain knowledge to + * pursue this. + * + * The goal and function of the following code is to support the two + * clock rates used by the audio subsystem, allowing for proper audio + * playback and capture without any pitch or speed changes. + */ +bool ccu_sdm_helper_has_rate(struct ccu_common *common, + struct ccu_sdm_internal *sdm, + unsigned long rate) +{ + unsigned int i; + + if (!(common->features & CCU_FEATURE_SIGMA_DELTA_MOD)) + return false; + + for (i = 0; i < sdm->table_size; i++) + if (sdm->table[i].rate == rate) + return true; + + return false; +} + +unsigned long ccu_sdm_helper_read_rate(struct ccu_common *common, + struct ccu_sdm_internal *sdm, + u32 m, u32 n) +{ + unsigned int i; + u32 reg; + + pr_debug("%s: Read sigma-delta modulation setting\n", + clk_hw_get_name(&common->hw)); + + if (!(common->features & CCU_FEATURE_SIGMA_DELTA_MOD)) + return 0; + + pr_debug("%s: clock is sigma-delta modulated\n", + clk_hw_get_name(&common->hw)); + + reg = readl(common->base + sdm->tuning_reg); + + pr_debug("%s: pattern reg is 0x%x", + clk_hw_get_name(&common->hw), reg); + + for (i = 0; i < sdm->table_size; i++) + if (sdm->table[i].pattern == reg && + sdm->table[i].m == m && sdm->table[i].n == n) + return sdm->table[i].rate; + + /* We can't calculate the effective clock rate, so just fail. */ + return 0; +} + +int ccu_sdm_helper_get_factors(struct ccu_common *common, + struct ccu_sdm_internal *sdm, + unsigned long rate, + unsigned long *m, unsigned long *n) +{ + unsigned int i; + + if (!(common->features & CCU_FEATURE_SIGMA_DELTA_MOD)) + return -EINVAL; + + for (i = 0; i < sdm->table_size; i++) + if (sdm->table[i].rate == rate) { + *m = sdm->table[i].m; + *n = sdm->table[i].n; + return 0; + } + + /* nothing found */ + return -EINVAL; +} |