[PATCH 2/2] clk: renesas: rzg2l: Register PM notifier to disable unused clocks

Claudiu
2025-08-21T10:49:01Z

From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>

Register a PM notifier to disable unused clocks after system resume.
This is necessary when resuming from a low-power mode where the bootloader
re-enables certain module clocks for its own use.

To avoid keeping these clocks enabled after control is passed back to
Linux, call clk_disable_unused() from a PM_POST_SUSPEND notifier.

Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
---
drivers/clk/renesas/rzg2l-cpg.c | 24 ++++++++++++++++++++++++
1 file changed, 24 insertions(+)

diff --git a/drivers/clk/renesas/rzg2l-cpg.c b/drivers/clk/renesas/rzg2l-cpg.c
index 187233302818..2ca32d7acaf7 100644
--- a/drivers/clk/renesas/rzg2l-cpg.c
+++ b/drivers/clk/renesas/rzg2l-cpg.c
@@ -24,6 +24,7 @@
#include <linux/iopoll.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
+#include <linux/notifier.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/pm_clock.h>
@@ -31,6 +32,7 @@
#include <linux/reset-controller.h>
#include <linux/slab.h>
#include <linux/string_choices.h>
+#include <linux/suspend.h>
#include <linux/units.h>

#include <dt-bindings/clock/renesas-cpg-mssr.h>
@@ -150,6 +152,7 @@ struct rzg2l_pll5_mux_dsi_div_param {
* @info: Pointer to platform data
* @genpd: PM domain
* @mux_dsi_div_params: pll5 mux and dsi div parameters
+ * @pm_notifier: PM notifier
*/
struct rzg2l_cpg_priv {
struct reset_controller_dev rcdev;
@@ -168,6 +171,8 @@ struct rzg2l_cpg_priv {
struct generic_pm_domain genpd;

struct rzg2l_pll5_mux_dsi_div_param mux_dsi_div_params;
+
+ struct notifier_block pm_notifier;
};

static void rzg2l_cpg_del_clk_provider(void *data)
@@ -1879,6 +1884,21 @@ static int __init rzg2l_cpg_add_clk_domain(struct rzg2l_cpg_priv *priv)
return of_genpd_add_provider_simple(np, genpd);
}

+static int rzg2l_pm_notifier(struct notifier_block *nb, unsigned long action,
+ void *data)
+{
+ int ret;
+
+ if (action != PM_POST_SUSPEND)
+ return 0;
+
+ ret = clk_disable_unused();
+ if (ret)
+ return NOTIFY_BAD;
+
+ return NOTIFY_OK;
+}
+
static int __init rzg2l_cpg_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
@@ -1948,6 +1968,10 @@ static int __init rzg2l_cpg_probe(struct platform_device *pdev)
return error;

debugfs_create_file("mstop", 0444, NULL, priv, &rzg2l_mod_clock_mstop_fops);
+
+ priv->pm_notifier.notifier_call = rzg2l_pm_notifier;
+ register_pm_notifier(&priv->pm_notifier);
+
return 0;
}

--
2.43.0