[PATCH v5 1/2] clk: starfive: jh7110-sys: Add notifier for PLL0 clock

Xingyu Wu
2024-05-07T08:25:59Z

Add notifier function for PLL0 clock. In the function, the cpu_root clock
should be operated by saving its current parent and setting a new safe
parent (osc clock) before setting the PLL0 clock rate. After setting PLL0
rate, it should be switched back to the original parent clock.

Fixes: e2c510d6d630 ("riscv: dts: starfive: Add cpu scaling for JH7110 SoC")
Signed-off-by: Xingyu Wu <xingyu.wu@starfivetech.com>
---
.../clk/starfive/clk-starfive-jh7110-sys.c | 31 ++++++++++++++++++-
drivers/clk/starfive/clk-starfive-jh71x0.h | 2 ++
2 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/drivers/clk/starfive/clk-starfive-jh7110-sys.c b/drivers/clk/starfive/clk-starfive-jh7110-sys.c
index 8f5e5abfa178..dafa3ae71751 100644
--- a/drivers/clk/starfive/clk-starfive-jh7110-sys.c
+++ b/drivers/clk/starfive/clk-starfive-jh7110-sys.c
@@ -385,6 +385,32 @@ int jh7110_reset_controller_register(struct jh71x0_clk_priv *priv,
}
EXPORT_SYMBOL_GPL(jh7110_reset_controller_register);

+/*
+ * This clock notifier is called when the rate of PLL0 clock is to be changed.
+ * The cpu_root clock should save the curent parent clock and swicth its parent
+ * clock to osc before PLL0 rate will be changed. Then swicth its parent clock
+ * back after the PLL0 rate is completed.
+ */
+static int jh7110_pll0_clk_notifier_cb(struct notifier_block *nb,
+ unsigned long action, void *data)
+{
+ struct jh71x0_clk_priv *priv = container_of(nb, struct jh71x0_clk_priv, pll_clk_nb);
+ struct clk *cpu_root = priv->reg[JH7110_SYSCLK_CPU_ROOT].hw.clk;
+ int ret = 0;
+
+ if (action == PRE_RATE_CHANGE) {
+ struct clk *osc = clk_get(priv->dev, "osc");
+
+ priv->original_clk = clk_get_parent(cpu_root);
+ ret = clk_set_parent(cpu_root, osc);
+ clk_put(osc);
+ } else if (action == POST_RATE_CHANGE) {
+ ret = clk_set_parent(cpu_root, priv->original_clk);
+ }
+
+ return notifier_from_errno(ret);
+}
+
static int __init jh7110_syscrg_probe(struct platform_device *pdev)
{
struct jh71x0_clk_priv *priv;
@@ -413,7 +439,10 @@ static int __init jh7110_syscrg_probe(struct platform_device *pdev)
if (IS_ERR(priv->pll[0]))
return PTR_ERR(priv->pll[0]);
} else {
- clk_put(pllclk);
+ priv->pll_clk_nb.notifier_call = jh7110_pll0_clk_notifier_cb;
+ ret = clk_notifier_register(pllclk, &priv->pll_clk_nb);
+ if (ret)
+ return ret;
priv->pll[0] = NULL;
}

diff --git a/drivers/clk/starfive/clk-starfive-jh71x0.h b/drivers/clk/starfive/clk-starfive-jh71x0.h
index 23e052fc1549..e3f441393e48 100644
--- a/drivers/clk/starfive/clk-starfive-jh71x0.h
+++ b/drivers/clk/starfive/clk-starfive-jh71x0.h
@@ -114,6 +114,8 @@ struct jh71x0_clk_priv {
spinlock_t rmw_lock;
struct device *dev;
void __iomem *base;
+ struct clk *original_clk;
+ struct notifier_block pll_clk_nb;
struct clk_hw *pll[3];
struct jh71x0_clk reg[];
};
--
2.25.1