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clk: tegra: cclk: Add helpers for handling PLLX rate changes

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CCLK should be re-parented away from PLLX if PLLX's rate is changing.
The PLLP parent is a common safe CPU parent for all Tegra SoCs, thus
CCLK will be re-parented to PLLP before PLLX rate-change begins and then
switched back to PLLX after the rate-change completion. This patch adds
helper functions which perform CCLK re-parenting, these helpers will be
utilized by further patches.

Acked-by: Peter De Schrijver <pdeschrijver@nvidia.com>
Tested-by: Peter Geis <pgwipeout@gmail.com>
Tested-by: Marcel Ziswiler <marcel@ziswiler.com>
Tested-by: Jasper Korten <jja2000@gmail.com>
Tested-by: David Heidelberg <david@ixit.cz>
Tested-by: Nicolas Chauvet <kwizart@gmail.com>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
This commit is contained in:
Dmitry Osipenko 2020-03-19 22:02:20 +03:00 committed by Thierry Reding
parent 9157abe74b
commit dec15c9901
2 changed files with 36 additions and 0 deletions
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34
drivers/clk/tegra/clk-tegra-super-cclk.c
View File

@ -25,6 +25,9 @@
#define SUPER_CDIV_ENB BIT(31)
static struct tegra_clk_super_mux *cclk_super;
static bool cclk_on_pllx;
static u8 cclk_super_get_parent(struct clk_hw *hw)
{
return tegra_clk_super_ops.get_parent(hw);
@ -115,6 +118,9 @@ struct clk *tegra_clk_register_super_cclk(const char *name,
struct clk_init_data init;
u32 val;
if (WARN_ON(cclk_super))
return ERR_PTR(-EBUSY);
super = kzalloc(sizeof(*super), GFP_KERNEL);
if (!super)
return ERR_PTR(-ENOMEM);
@ -173,6 +179,34 @@ struct clk *tegra_clk_register_super_cclk(const char *name,
clk = clk_register(NULL, &super->hw);
if (IS_ERR(clk))
kfree(super);
else
cclk_super = super;
return clk;
}
int tegra_cclk_pre_pllx_rate_change(void)
{
if (IS_ERR_OR_NULL(cclk_super))
return -EINVAL;
if (cclk_super_get_parent(&cclk_super->hw) == PLLX_INDEX)
cclk_on_pllx = true;
else
cclk_on_pllx = false;
/*
* CPU needs to be temporarily re-parented away from PLLX if PLLX
* changes its rate. PLLP is a safe parent for CPU on all Tegra SoCs.
*/
if (cclk_on_pllx)
cclk_super_set_parent(&cclk_super->hw, PLLP_INDEX);
return 0;
}
void tegra_cclk_post_pllx_rate_change(void)
{
if (cclk_on_pllx)
cclk_super_set_parent(&cclk_super->hw, PLLX_INDEX);
}

2
drivers/clk/tegra/clk.h
View File

@ -771,6 +771,8 @@ struct clk *tegra_clk_register_super_cclk(const char *name,
const char * const *parent_names, u8 num_parents,
unsigned long flags, void __iomem *reg, u8 clk_super_flags,
spinlock_t *lock);
int tegra_cclk_pre_pllx_rate_change(void);
void tegra_cclk_post_pllx_rate_change(void);
/**
* struct tegra_sdmmc_mux - switch divider with Low Jitter inputs for SDMMC