[PATCH] clk: renesas: mstp: Add genpd OF provider at postcore_initcall()

[Geert Uytterhoeven <geert+renesas@xxxxxxxxx>]

Genpd OF providers must now be registered after genpd bus registration.
However, cpg_mstp_add_clk_domain() is only called from CLK_OF_DECLARE(),
which is too early.  Hence on R-Car M1A, R-Car H1, and RZ/A1, the
CPG/MSTP Clock Domain fails to register, and any devices residing in
that clock domain fail to probe.

Fix this by splitting initialization into two steps:
  - The first part keeps on registering the PM domain with genpd at
    CLK_OF_DECLARE(),
  - The second and new part moves the registration of the genpd OF
    provider to a postcore_initcall().

See also commit c5ae5a0c61120d0c ("pmdomain: renesas: rcar-sysc: Add
genpd OF provider at postcore_initcall").

Fixes: 18a3a510ecfd0e50 ("pmdomain: core: Add the genpd->dev to the genpd provider bus")
Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
---
To be queued as a fix in renesas-clk-for-v6.17.

drivers/clk/mmp/clk-of-mmp2.c:mmp2_pm_domain_init() has the same issue.

Note that R-Car H1 still booted fine, as the CPG/MSTP Clock Domain is no
longer used directly on that SoC: all devices were moved to the R-Car
SYSC PM Domain in commits 751e29bbb64ad091 ("ARM: dts: r8a7779: Use SYSC
"always-on" PM Domain") and commit a03fa77d85a736d3 ("ARM: dts: r8a7779:
Use SYSC "always-on" PM Domain for HSCIF"), and use the clock domain
only indirectly from rcar-sysc through cpg_mstp_{at,de}tach_dev()).
---
 drivers/clk/renesas/clk-mstp.c | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/drivers/clk/renesas/clk-mstp.c b/drivers/clk/renesas/clk-mstp.c
index 6b47bb5eee45f75b..5fcc81b92a973771 100644
--- a/drivers/clk/renesas/clk-mstp.c
+++ b/drivers/clk/renesas/clk-mstp.c
@@ -305,6 +305,9 @@ void cpg_mstp_detach_dev(struct generic_pm_domain *unused, struct device *dev)
 		pm_clk_destroy(dev);
 }
 
+static struct device_node *cpg_mstp_pd_np __initdata = NULL;
+static struct generic_pm_domain *cpg_mstp_pd_genpd __initdata = NULL;
+
 void __init cpg_mstp_add_clk_domain(struct device_node *np)
 {
 	struct generic_pm_domain *pd;
@@ -326,5 +329,20 @@ void __init cpg_mstp_add_clk_domain(struct device_node *np)
 	pd->detach_dev = cpg_mstp_detach_dev;
 	pm_genpd_init(pd, &pm_domain_always_on_gov, false);
 
-	of_genpd_add_provider_simple(np, pd);
+	cpg_mstp_pd_np = of_node_get(np);
+	cpg_mstp_pd_genpd = pd;
+}
+
+static int __init cpg_mstp_pd_init_provider(void)
+{
+	int error;
+
+	if (!cpg_mstp_pd_np)
+		return -ENODEV;
+
+	error = of_genpd_add_provider_simple(cpg_mstp_pd_np, cpg_mstp_pd_genpd);
+
+	of_node_put(cpg_mstp_pd_np);
+	return error;
 }
+postcore_initcall(cpg_mstp_pd_init_provider);
-- 
2.43.0