clk: at91: pmc: execute suspend/resume only for backup mode

Before going to backup mode architecture specific PM code sets the first
word in securam (file arch/arm/mach-at91/pm.c, function at91_pm_begin()).
Thus take this into account when suspending/resuming clocks. This will
avoid executing unnecessary instructions when suspending to non backup
modes.

Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Link: https://lore.kernel.org/r/20211011112719.3951784-3-claudiu.beznea@microchip.com
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

diff --git a/drivers/clk/at91/pmc.c b/drivers/clk/at91/pmc.c
index b280694..5179730 100644 (file)
--- a/drivers/clk/at91/pmc.c
+++ b/drivers/clk/at91/pmc.c
@@ -8,6 +8,7 @@
 #include <linux/clkdev.h>
 #include <linux/clk/at91_pmc.h>
 #include <linux/of.h>
+#include <linux/of_address.h>
 #include <linux/mfd/syscon.h>
 #include <linux/platform_device.h>
 #include <linux/regmap.h>
@@ -110,13 +111,35 @@ 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 = readl_relaxed(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 = readl_relaxed(at91_pmc_backup_suspend);
+       if (!backup)
+               return;
+
        clk_restore_context();
 }
 
@@ -144,6 +167,22 @@ static int __init pmc_register_ops(void)
        }
        of_node_put(np);
 
+       np = of_find_compatible_node(NULL, NULL, "atmel,sama5d2-securam");
+       if (!np)
+               return -ENODEV;
+
+       if (!of_device_is_available(np)) {
+               of_node_put(np);
+               return -ENODEV;
+       }
+       of_node_put(np);
+
+       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;