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/*
* 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;
}
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