[PATCH v2 2/6] clk: at91: pmc: execute suspend/resume only for backup mode

[Claudiu Beznea <claudiu.beznea@microchip.com>]

Before going to backup mode architecture specific PM code sets the first
word in securam (and it will be cleared in a subsequent commit for the rest
of power saving modes). Thus take this into account when
suspending/resuming clocks. This will avoid executing unnecessary
instructions when suspending to non backup modes. Since the clear of the
1st word in securam will be done in a subsequent commit the current commit
will not broke the current behavior since up to this moment the
suspend/resume were executed for all AT91 PM modes. The difference now
is that the suspend/resume for clocks will be executed for the rest of
AT91 PM modes just after the 1st enter/exit to/from backup mode.
Also this commit changed the postcore_initcall() with subsys_initcall()
to be able to execute of_find_compatible_node() since this was not
available at the moment of postcore_initcall(). This should not alter
the tcb_clksrc since the changes are related to clocks suspend/resume
procedure that will be executed at the user space request, thus long
ago after postcore_initcall().

Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
---
 drivers/clk/at91/pmc.c | 48 ++++++++++++++++++++++++++++++++++--------
 1 file changed, 39 insertions(+), 9 deletions(-)

diff --git a/drivers/clk/at91/pmc.c b/drivers/clk/at91/pmc.c
index 77b57c9f5dcb..c226d33cd899 100644
--- a/drivers/clk/at91/pmc.c
+++ b/drivers/clk/at91/pmc.c
@@ -8,6 +8,8 @@
 #include <linux/clkdev.h>
 #include <linux/clk/at91_pmc.h>
 #include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_platform.h>
 #include <linux/mfd/syscon.h>
 #include <linux/platform_device.h>
 #include <linux/regmap.h>
@@ -110,13 +112,35 @@ struct pmc_data *pmc_data_allocate(unsigned int ncore, unsigned int nsystem,
 }
 
 #ifdef CONFIG_PM
+
+/* Address in SECURAM that say if we suspend to backup mode. */
+static void __iomem *at91_pmc_backup_suspend;
+
 static int at91_pmc_suspend(void)
 {
+	unsigned int backup;
+
+	if (!at91_pmc_backup_suspend)
+		return 0;
+
+	backup = *(unsigned int *)at91_pmc_backup_suspend;
+	if (!backup)
+		return 0;
+
 	return clk_save_context();
 }
 
 static void at91_pmc_resume(void)
 {
+	unsigned int backup;
+
+	if (!at91_pmc_backup_suspend)
+		return;
+
+	backup = *(unsigned int *)at91_pmc_backup_suspend;
+	if (!backup)
+		return;
+
 	clk_restore_context();
 }
 
@@ -125,24 +149,30 @@ static struct syscore_ops pmc_syscore_ops = {
 	.resume = at91_pmc_resume,
 };
 
-static const struct of_device_id sama5d2_pmc_dt_ids[] = {
-	{ .compatible = "atmel,sama5d2-pmc" },
-	{ /* sentinel */ }
-};
-
 static int __init pmc_register_ops(void)
 {
+	struct platform_device *pdev;
 	struct device_node *np;
 
-	np = of_find_matching_node(NULL, sama5d2_pmc_dt_ids);
+	np = of_find_compatible_node(NULL, NULL, "atmel,sama5d2-securam");
 	if (!np)
-		return 0;
+		return -ENODEV;
+
+	pdev = of_find_device_by_node(np);
 	of_node_put(np);
+	if (!pdev)
+		return -ENODEV;
+
+	at91_pmc_backup_suspend = of_iomap(np, 0);
+	if (!at91_pmc_backup_suspend) {
+		pr_warn("%s(): unable to map securam\n", __func__);
+		return -ENOMEM;
+	}
 
 	register_syscore_ops(&pmc_syscore_ops);
 
 	return 0;
 }
-/* This has to happen before arch_initcall because of the tcb_clksrc driver */
-postcore_initcall(pmc_register_ops);
+
+subsys_initcall(pmc_register_ops);
 #endif
-- 
2.25.1