clk: renesas: cpg-mssr: Export cpg_mssr_{at,de}tach_dev()

The R-Car SYSC PM Domain driver has to power manage devices in power
areas using clocks. To reuse code and to share knowledge of clocks
suitable for power management, this is ideally done through the existing
cpg_mssr_attach_dev() and cpg_mssr_detach_dev() callbacks.

Hence these callbacks can no longer rely on their "domain" parameter
pointing to the CPG/MSSR Clock Domain. To handle this, keep a pointer to
the clock domain in a static variable. cpg_mssr_attach_dev() has to
support probe deferral, as the R-Car SYSC PM Domain may be initialized,
and devices may be added to it, before the CPG/MSSR Clock Domain is
initialized.

Dummy callbacks are provided for the case where CPG/MSTP support is not
included, so the rcar-sysc driver won't have to care about this.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

drivers/clk/renesas/renesas-cpg-mssr.c

@@ -15,6 +15,7 @@
 
 #include <linux/clk.h>
 #include <linux/clk-provider.h>
+#include <linux/clk/renesas.h>
 #include <linux/device.h>
 #include <linux/init.h>
 #include <linux/mod_devicetable.h>
@@ -388,6 +389,8 @@ struct cpg_mssr_clk_domain {
 	unsigned int core_pm_clks[0];
 };
 
+static struct cpg_mssr_clk_domain *cpg_mssr_clk_domain;
+
 static bool cpg_mssr_is_pm_clk(const struct of_phandle_args *clkspec,
 			       struct cpg_mssr_clk_domain *pd)
 {
@@ -411,17 +414,20 @@ static bool cpg_mssr_is_pm_clk(const struct of_phandle_args *clkspec,
 	}
 }
 
-static int cpg_mssr_attach_dev(struct generic_pm_domain *genpd,
-			       struct device *dev)
+int cpg_mssr_attach_dev(struct generic_pm_domain *unused, struct device *dev)
 {
-	struct cpg_mssr_clk_domain *pd =
-		container_of(genpd, struct cpg_mssr_clk_domain, genpd);
+	struct cpg_mssr_clk_domain *pd = cpg_mssr_clk_domain;
 	struct device_node *np = dev->of_node;
 	struct of_phandle_args clkspec;
 	struct clk *clk;
 	int i = 0;
 	int error;
 
+	if (!pd) {
+		dev_dbg(dev, "CPG/MSSR clock domain not yet available\n");
+		return -EPROBE_DEFER;
+	}
+
 	while (!of_parse_phandle_with_args(np, "clocks", "#clock-cells", i,
 					   &clkspec)) {
 		if (cpg_mssr_is_pm_clk(&clkspec, pd))
@@ -461,8 +467,7 @@ static int cpg_mssr_attach_dev(struct generic_pm_domain *genpd,
 	return error;
 }
 
-static void cpg_mssr_detach_dev(struct generic_pm_domain *genpd,
-				struct device *dev)
+void cpg_mssr_detach_dev(struct generic_pm_domain *unused, struct device *dev)
 {
 	if (!list_empty(&dev->power.subsys_data->clock_list))
 		pm_clk_destroy(dev);
@@ -491,6 +496,7 @@ static int __init cpg_mssr_add_clk_domain(struct device *dev,
 	pm_genpd_init(genpd, &simple_qos_governor, false);
 	genpd->attach_dev = cpg_mssr_attach_dev;
 	genpd->detach_dev = cpg_mssr_detach_dev;
+	cpg_mssr_clk_domain = pd;
 
 	of_genpd_add_provider_simple(np, genpd);
 	return 0;

include/linux/clk/renesas.h

@@ -33,4 +33,11 @@ void cpg_mstp_detach_dev(struct generic_pm_domain *unused, struct device *dev);
 #define cpg_mstp_detach_dev	NULL
 #endif
 
+#ifdef CONFIG_CLK_RENESAS_CPG_MSSR
+int cpg_mssr_attach_dev(struct generic_pm_domain *unused, struct device *dev);
+void cpg_mssr_detach_dev(struct generic_pm_domain *unused, struct device *dev);
+#else
+#define cpg_mssr_attach_dev	NULL
+#define cpg_mssr_detach_dev	NULL
+#endif
 #endif