[PATCH v5 12/15] clk: at91: clk-master: add notifier for divider
Claudiu Beznea
claudiu.beznea at microchip.com
Mon Oct 11 04:27:16 PDT 2021
SAMA7G5 supports DVFS by changing cpuck. On SAMA7G5 mck0 shares the same
parent with cpuck as seen in the following clock tree:
+----------> cpuck
|
FRAC PLL ---> DIV PLL -+-> DIV ---> mck0
mck0 could go b/w 32KHz and 200MHz on SAMA7G5. To avoid mck0 overclocking
while changing FRAC PLL or DIV PLL the commit implements a notifier for
mck0 which applies a safe divider to register (maximum value of the divider
which is 5) on PRE_RATE_CHANGE events (such that changes on PLL to not
overclock mck0) and sets the maximum allowed rate on POST_RATE_CHANGE
events.
Signed-off-by: Claudiu Beznea <claudiu.beznea at microchip.com>
---
drivers/clk/at91/at91rm9200.c | 2 +-
drivers/clk/at91/at91sam9260.c | 2 +-
drivers/clk/at91/at91sam9g45.c | 2 +-
drivers/clk/at91/at91sam9n12.c | 2 +-
drivers/clk/at91/at91sam9rl.c | 2 +-
drivers/clk/at91/at91sam9x5.c | 2 +-
drivers/clk/at91/clk-master.c | 244 +++++++++++++++++++++++----------
drivers/clk/at91/dt-compat.c | 2 +-
drivers/clk/at91/pmc.h | 2 +-
drivers/clk/at91/sama5d2.c | 2 +-
drivers/clk/at91/sama5d3.c | 2 +-
drivers/clk/at91/sama5d4.c | 2 +-
drivers/clk/at91/sama7g5.c | 2 +-
13 files changed, 186 insertions(+), 82 deletions(-)
diff --git a/drivers/clk/at91/at91rm9200.c b/drivers/clk/at91/at91rm9200.c
index 428a6f4b9ebc..fff4fdda974f 100644
--- a/drivers/clk/at91/at91rm9200.c
+++ b/drivers/clk/at91/at91rm9200.c
@@ -152,7 +152,7 @@ static void __init at91rm9200_pmc_setup(struct device_node *np)
"masterck_pres",
&at91rm9200_master_layout,
&rm9200_mck_characteristics,
- &rm9200_mck_lock, CLK_SET_RATE_GATE);
+ &rm9200_mck_lock, CLK_SET_RATE_GATE, 0);
if (IS_ERR(hw))
goto err_free;
diff --git a/drivers/clk/at91/at91sam9260.c b/drivers/clk/at91/at91sam9260.c
index b29843bea278..79802f864ee5 100644
--- a/drivers/clk/at91/at91sam9260.c
+++ b/drivers/clk/at91/at91sam9260.c
@@ -429,7 +429,7 @@ static void __init at91sam926x_pmc_setup(struct device_node *np,
&at91rm9200_master_layout,
data->mck_characteristics,
&at91sam9260_mck_lock,
- CLK_SET_RATE_GATE);
+ CLK_SET_RATE_GATE, 0);
if (IS_ERR(hw))
goto err_free;
diff --git a/drivers/clk/at91/at91sam9g45.c b/drivers/clk/at91/at91sam9g45.c
index 15da0dfe3ef2..7ed984f8058c 100644
--- a/drivers/clk/at91/at91sam9g45.c
+++ b/drivers/clk/at91/at91sam9g45.c
@@ -164,7 +164,7 @@ static void __init at91sam9g45_pmc_setup(struct device_node *np)
&at91rm9200_master_layout,
&mck_characteristics,
&at91sam9g45_mck_lock,
- CLK_SET_RATE_GATE);
+ CLK_SET_RATE_GATE, 0);
if (IS_ERR(hw))
goto err_free;
diff --git a/drivers/clk/at91/at91sam9n12.c b/drivers/clk/at91/at91sam9n12.c
index 7fe435f4b46b..63cc58944b00 100644
--- a/drivers/clk/at91/at91sam9n12.c
+++ b/drivers/clk/at91/at91sam9n12.c
@@ -191,7 +191,7 @@ static void __init at91sam9n12_pmc_setup(struct device_node *np)
&at91sam9x5_master_layout,
&mck_characteristics,
&at91sam9n12_mck_lock,
- CLK_SET_RATE_GATE);
+ CLK_SET_RATE_GATE, 0);
if (IS_ERR(hw))
goto err_free;
diff --git a/drivers/clk/at91/at91sam9rl.c b/drivers/clk/at91/at91sam9rl.c
index ecbabf5162bd..4d4faf6c61d8 100644
--- a/drivers/clk/at91/at91sam9rl.c
+++ b/drivers/clk/at91/at91sam9rl.c
@@ -132,7 +132,7 @@ static void __init at91sam9rl_pmc_setup(struct device_node *np)
"masterck_pres",
&at91rm9200_master_layout,
&sam9rl_mck_characteristics,
- &sam9rl_mck_lock, CLK_SET_RATE_GATE);
+ &sam9rl_mck_lock, CLK_SET_RATE_GATE, 0);
if (IS_ERR(hw))
goto err_free;
diff --git a/drivers/clk/at91/at91sam9x5.c b/drivers/clk/at91/at91sam9x5.c
index 5cce48c64ea2..bd8007b4f3e0 100644
--- a/drivers/clk/at91/at91sam9x5.c
+++ b/drivers/clk/at91/at91sam9x5.c
@@ -210,7 +210,7 @@ static void __init at91sam9x5_pmc_setup(struct device_node *np,
"masterck_pres",
&at91sam9x5_master_layout,
&mck_characteristics, &mck_lock,
- CLK_SET_RATE_GATE);
+ CLK_SET_RATE_GATE, 0);
if (IS_ERR(hw))
goto err_free;
diff --git a/drivers/clk/at91/clk-master.c b/drivers/clk/at91/clk-master.c
index e67bcd03a827..b2d0a7f4f7f9 100644
--- a/drivers/clk/at91/clk-master.c
+++ b/drivers/clk/at91/clk-master.c
@@ -5,6 +5,7 @@
#include <linux/clk-provider.h>
#include <linux/clkdev.h>
+#include <linux/clk.h>
#include <linux/clk/at91_pmc.h>
#include <linux/of.h>
#include <linux/mfd/syscon.h>
@@ -36,8 +37,12 @@ struct clk_master {
u8 id;
u8 parent;
u8 div;
+ u32 safe_div;
};
+/* MCK div reference to be used by notifier. */
+static struct clk_master *master_div;
+
static inline bool clk_master_ready(struct clk_master *master)
{
unsigned int bit = master->id ? AT91_PMC_MCKXRDY : AT91_PMC_MCKRDY;
@@ -153,107 +158,81 @@ static const struct clk_ops master_div_ops = {
.restore_context = clk_master_div_restore_context,
};
-static int clk_master_div_set_rate(struct clk_hw *hw, unsigned long rate,
- unsigned long parent_rate)
+/* This function must be called with lock acquired. */
+static int clk_master_div_set(struct clk_master *master,
+ unsigned long parent_rate, int div)
{
- struct clk_master *master = to_clk_master(hw);
const struct clk_master_characteristics *characteristics =
master->characteristics;
- unsigned long flags;
- unsigned int mckr, tmp;
- int div, i;
+ unsigned long rate = parent_rate;
+ unsigned int max_div = 0, div_index = 0, max_div_index = 0;
+ unsigned int i, mckr, tmp;
int ret;
- div = DIV_ROUND_CLOSEST(parent_rate, rate);
- if (div > ARRAY_SIZE(characteristics->divisors))
- return -EINVAL;
-
for (i = 0; i < ARRAY_SIZE(characteristics->divisors); i++) {
if (!characteristics->divisors[i])
break;
- if (div == characteristics->divisors[i]) {
- div = i;
- break;
+ if (div == characteristics->divisors[i])
+ div_index = i;
+
+ if (max_div < characteristics->divisors[i]) {
+ max_div = characteristics->divisors[i];
+ max_div_index = i;
}
}
- if (i == ARRAY_SIZE(characteristics->divisors))
- return -EINVAL;
+ if (div > max_div)
+ div_index = max_div_index;
- spin_lock_irqsave(master->lock, flags);
ret = regmap_read(master->regmap, master->layout->offset, &mckr);
if (ret)
- goto unlock;
+ return ret;
mckr &= master->layout->mask;
tmp = (mckr >> MASTER_DIV_SHIFT) & MASTER_DIV_MASK;
- if (tmp == div)
- goto unlock;
+ if (tmp == div_index)
+ return 0;
+
+ rate /= characteristics->divisors[div_index];
+ if (rate < characteristics->output.min)
+ pr_warn("master clk div is underclocked");
+ else if (rate > characteristics->output.max)
+ pr_warn("master clk div is overclocked");
mckr &= ~(MASTER_DIV_MASK << MASTER_DIV_SHIFT);
- mckr |= (div << MASTER_DIV_SHIFT);
+ mckr |= (div_index << MASTER_DIV_SHIFT);
ret = regmap_write(master->regmap, master->layout->offset, mckr);
if (ret)
- goto unlock;
+ return ret;
while (!clk_master_ready(master))
cpu_relax();
-unlock:
- spin_unlock_irqrestore(master->lock, flags);
+
+ master->div = characteristics->divisors[div_index];
return 0;
}
-static int clk_master_div_determine_rate(struct clk_hw *hw,
- struct clk_rate_request *req)
+static unsigned long clk_master_div_recalc_rate_chg(struct clk_hw *hw,
+ unsigned long parent_rate)
{
struct clk_master *master = to_clk_master(hw);
- const struct clk_master_characteristics *characteristics =
- master->characteristics;
- struct clk_hw *parent;
- unsigned long parent_rate, tmp_rate, best_rate = 0;
- int i, best_diff = INT_MIN, tmp_diff;
-
- parent = clk_hw_get_parent(hw);
- if (!parent)
- return -EINVAL;
-
- parent_rate = clk_hw_get_rate(parent);
- if (!parent_rate)
- return -EINVAL;
-
- for (i = 0; i < ARRAY_SIZE(characteristics->divisors); i++) {
- if (!characteristics->divisors[i])
- break;
- tmp_rate = DIV_ROUND_CLOSEST_ULL(parent_rate,
- characteristics->divisors[i]);
- tmp_diff = abs(tmp_rate - req->rate);
-
- if (!best_rate || best_diff > tmp_diff) {
- best_diff = tmp_diff;
- best_rate = tmp_rate;
- }
-
- if (!best_diff)
- break;
- }
-
- req->best_parent_rate = best_rate;
- req->best_parent_hw = parent;
- req->rate = best_rate;
-
- return 0;
+ return DIV_ROUND_CLOSEST_ULL(parent_rate, master->div);
}
static void clk_master_div_restore_context_chg(struct clk_hw *hw)
{
struct clk_master *master = to_clk_master(hw);
+ unsigned long flags;
int ret;
- ret = clk_master_div_set_rate(hw, master->pms.rate,
- master->pms.parent_rate);
+ spin_lock_irqsave(master->lock, flags);
+ ret = clk_master_div_set(master, master->pms.parent_rate,
+ DIV_ROUND_CLOSEST(master->pms.parent_rate,
+ master->pms.rate));
+ spin_unlock_irqrestore(master->lock, flags);
if (ret)
pr_warn("Failed to restore MCK DIV clock\n");
}
@@ -261,13 +240,116 @@ static void clk_master_div_restore_context_chg(struct clk_hw *hw)
static const struct clk_ops master_div_ops_chg = {
.prepare = clk_master_prepare,
.is_prepared = clk_master_is_prepared,
- .recalc_rate = clk_master_div_recalc_rate,
- .determine_rate = clk_master_div_determine_rate,
- .set_rate = clk_master_div_set_rate,
+ .recalc_rate = clk_master_div_recalc_rate_chg,
.save_context = clk_master_div_save_context,
.restore_context = clk_master_div_restore_context_chg,
};
+static int clk_master_div_notifier_fn(struct notifier_block *notifier,
+ unsigned long code, void *data)
+{
+ const struct clk_master_characteristics *characteristics =
+ master_div->characteristics;
+ struct clk_notifier_data *cnd = data;
+ unsigned long flags, new_parent_rate, new_rate;
+ unsigned int mckr, div, new_div = 0;
+ int ret, i;
+ long tmp_diff;
+ long best_diff = -1;
+
+ spin_lock_irqsave(master_div->lock, flags);
+ switch (code) {
+ case PRE_RATE_CHANGE:
+ /*
+ * We want to avoid any overclocking of MCK DIV domain. To do
+ * this we set a safe divider (the underclocking is not of
+ * interest as we can go as low as 32KHz). The relation
+ * b/w this clock and its parents are as follows:
+ *
+ * FRAC PLL -> DIV PLL -> MCK DIV
+ *
+ * With the proper safe divider we should be good even with FRAC
+ * PLL at its maximum value.
+ */
+ ret = regmap_read(master_div->regmap, master_div->layout->offset,
+ &mckr);
+ if (ret) {
+ ret = NOTIFY_STOP_MASK;
+ goto unlock;
+ }
+
+ mckr &= master_div->layout->mask;
+ div = (mckr >> MASTER_DIV_SHIFT) & MASTER_DIV_MASK;
+
+ /* Switch to safe divider. */
+ clk_master_div_set(master_div,
+ cnd->old_rate * characteristics->divisors[div],
+ master_div->safe_div);
+ break;
+
+ case POST_RATE_CHANGE:
+ /*
+ * At this point we want to restore MCK DIV domain to its maximum
+ * allowed rate.
+ */
+ ret = regmap_read(master_div->regmap, master_div->layout->offset,
+ &mckr);
+ if (ret) {
+ ret = NOTIFY_STOP_MASK;
+ goto unlock;
+ }
+
+ mckr &= master_div->layout->mask;
+ div = (mckr >> MASTER_DIV_SHIFT) & MASTER_DIV_MASK;
+ new_parent_rate = cnd->new_rate * characteristics->divisors[div];
+
+ for (i = 0; i < ARRAY_SIZE(characteristics->divisors); i++) {
+ if (!characteristics->divisors[i])
+ break;
+
+ new_rate = DIV_ROUND_CLOSEST_ULL(new_parent_rate,
+ characteristics->divisors[i]);
+
+ tmp_diff = characteristics->output.max - new_rate;
+ if (tmp_diff < 0)
+ continue;
+
+ if (best_diff < 0 || best_diff > tmp_diff) {
+ new_div = characteristics->divisors[i];
+ best_diff = tmp_diff;
+ }
+
+ if (!tmp_diff)
+ break;
+ }
+
+ if (!new_div) {
+ ret = NOTIFY_STOP_MASK;
+ goto unlock;
+ }
+
+ /* Update the div to preserve MCK DIV clock rate. */
+ clk_master_div_set(master_div, new_parent_rate,
+ new_div);
+
+ ret = NOTIFY_OK;
+ break;
+
+ default:
+ ret = NOTIFY_DONE;
+ break;
+ }
+
+unlock:
+ spin_unlock_irqrestore(master_div->lock, flags);
+
+ return ret;
+}
+
+static struct notifier_block clk_master_div_notifier = {
+ .notifier_call = clk_master_div_notifier_fn,
+};
+
static void clk_sama7g5_master_best_diff(struct clk_rate_request *req,
struct clk_hw *parent,
unsigned long parent_rate,
@@ -496,6 +578,8 @@ at91_clk_register_master_internal(struct regmap *regmap,
struct clk_master *master;
struct clk_init_data init;
struct clk_hw *hw;
+ unsigned int mckr;
+ unsigned long irqflags;
int ret;
if (!name || !num_parents || !parent_names || !lock)
@@ -518,6 +602,16 @@ at91_clk_register_master_internal(struct regmap *regmap,
master->chg_pid = chg_pid;
master->lock = lock;
+ if (ops == &master_div_ops_chg) {
+ spin_lock_irqsave(master->lock, irqflags);
+ regmap_read(master->regmap, master->layout->offset, &mckr);
+ spin_unlock_irqrestore(master->lock, irqflags);
+
+ mckr &= layout->mask;
+ mckr = (mckr >> MASTER_DIV_SHIFT) & MASTER_DIV_MASK;
+ master->div = characteristics->divisors[mckr];
+ }
+
hw = &master->hw;
ret = clk_hw_register(NULL, &master->hw);
if (ret) {
@@ -554,19 +648,29 @@ at91_clk_register_master_div(struct regmap *regmap,
const char *name, const char *parent_name,
const struct clk_master_layout *layout,
const struct clk_master_characteristics *characteristics,
- spinlock_t *lock, u32 flags)
+ spinlock_t *lock, u32 flags, u32 safe_div)
{
const struct clk_ops *ops;
+ struct clk_hw *hw;
if (flags & CLK_SET_RATE_GATE)
ops = &master_div_ops;
else
ops = &master_div_ops_chg;
- return at91_clk_register_master_internal(regmap, name, 1,
- &parent_name, layout,
- characteristics, ops,
- lock, flags, -EINVAL);
+ hw = at91_clk_register_master_internal(regmap, name, 1,
+ &parent_name, layout,
+ characteristics, ops,
+ lock, flags, -EINVAL);
+
+ if (!IS_ERR(hw) && safe_div) {
+ master_div = to_clk_master(hw);
+ master_div->safe_div = safe_div;
+ clk_notifier_register(hw->clk,
+ &clk_master_div_notifier);
+ }
+
+ return hw;
}
static unsigned long
diff --git a/drivers/clk/at91/dt-compat.c b/drivers/clk/at91/dt-compat.c
index a97b99c2dc12..ca2dbb65b9df 100644
--- a/drivers/clk/at91/dt-compat.c
+++ b/drivers/clk/at91/dt-compat.c
@@ -399,7 +399,7 @@ of_at91_clk_master_setup(struct device_node *np,
hw = at91_clk_register_master_div(regmap, name, "masterck_pres",
layout, characteristics,
- &mck_lock, CLK_SET_RATE_GATE);
+ &mck_lock, CLK_SET_RATE_GATE, 0);
if (IS_ERR(hw))
goto out_free_characteristics;
diff --git a/drivers/clk/at91/pmc.h b/drivers/clk/at91/pmc.h
index 207ecccef29f..3a1bf6194c28 100644
--- a/drivers/clk/at91/pmc.h
+++ b/drivers/clk/at91/pmc.h
@@ -182,7 +182,7 @@ at91_clk_register_master_div(struct regmap *regmap, const char *name,
const char *parent_names,
const struct clk_master_layout *layout,
const struct clk_master_characteristics *characteristics,
- spinlock_t *lock, u32 flags);
+ spinlock_t *lock, u32 flags, u32 safe_div);
struct clk_hw * __init
at91_clk_sama7g5_register_master(struct regmap *regmap,
diff --git a/drivers/clk/at91/sama5d2.c b/drivers/clk/at91/sama5d2.c
index 3d1f78176c3e..d027294a0089 100644
--- a/drivers/clk/at91/sama5d2.c
+++ b/drivers/clk/at91/sama5d2.c
@@ -249,7 +249,7 @@ static void __init sama5d2_pmc_setup(struct device_node *np)
"masterck_pres",
&at91sam9x5_master_layout,
&mck_characteristics, &mck_lock,
- CLK_SET_RATE_GATE);
+ CLK_SET_RATE_GATE, 0);
if (IS_ERR(hw))
goto err_free;
diff --git a/drivers/clk/at91/sama5d3.c b/drivers/clk/at91/sama5d3.c
index d376257807d2..339d0f382ff0 100644
--- a/drivers/clk/at91/sama5d3.c
+++ b/drivers/clk/at91/sama5d3.c
@@ -184,7 +184,7 @@ static void __init sama5d3_pmc_setup(struct device_node *np)
"masterck_pres",
&at91sam9x5_master_layout,
&mck_characteristics, &mck_lock,
- CLK_SET_RATE_GATE);
+ CLK_SET_RATE_GATE, 0);
if (IS_ERR(hw))
goto err_free;
diff --git a/drivers/clk/at91/sama5d4.c b/drivers/clk/at91/sama5d4.c
index 5cbaac68da44..4af75b1e39e9 100644
--- a/drivers/clk/at91/sama5d4.c
+++ b/drivers/clk/at91/sama5d4.c
@@ -199,7 +199,7 @@ static void __init sama5d4_pmc_setup(struct device_node *np)
"masterck_pres",
&at91sam9x5_master_layout,
&mck_characteristics, &mck_lock,
- CLK_SET_RATE_GATE);
+ CLK_SET_RATE_GATE, 0);
if (IS_ERR(hw))
goto err_free;
diff --git a/drivers/clk/at91/sama7g5.c b/drivers/clk/at91/sama7g5.c
index ae52c10af040..c66bde6f7b47 100644
--- a/drivers/clk/at91/sama7g5.c
+++ b/drivers/clk/at91/sama7g5.c
@@ -1003,7 +1003,7 @@ static void __init sama7g5_pmc_setup(struct device_node *np)
hw = at91_clk_register_master_div(regmap, "mck0", "cpuck",
&mck0_layout, &mck0_characteristics,
- &pmc_mck0_lock, 0);
+ &pmc_mck0_lock, CLK_GET_RATE_NOCACHE, 5);
if (IS_ERR(hw))
goto err_free;
--
2.25.1
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