@@ -598,7 +598,21 @@ static int at91_suspend_finish(unsigned long val)
return 0;
}
-static void at91_pm_switch_ba_to_vbat(void)
+/**
+ * at91_pm_switch_ba_to_auto() - Configure Backup Unit Power Switch
+ * to automatic/hardware mode.
+ *
+ * The Backup Unit Power Switch can be managed either by software or hardware.
+ * Enabling hardware mode allows the automatic transition of power between
+ * VDDANA (or VDDIN33) and VDDBU (or VBAT, respectively), based on the
+ * availability of these power sources.
+ *
+ * If the Backup Unit Power Switch is already in automatic mode, no action is
+ * required. If it is in software-controlled mode, it is switched to automatic
+ * mode to enhance safety and eliminate the need for toggling between power
+ * sources.
+ */
+static void at91_pm_switch_ba_to_auto(void)
{
unsigned int offset = offsetof(struct at91_pm_sfrbu_regs, pswbu);
unsigned int val;
@@ -609,24 +623,19 @@ static void at91_pm_switch_ba_to_vbat(void)
val = readl(soc_pm.data.sfrbu + offset);
- /* Already on VBAT. */
- if (!(val & soc_pm.sfrbu_regs.pswbu.state))
+ /* Already on auto/hardware. */
+ if (!(val & soc_pm.sfrbu_regs.pswbu.ctrl))
return;
- val &= ~soc_pm.sfrbu_regs.pswbu.softsw;
- val |= soc_pm.sfrbu_regs.pswbu.key | soc_pm.sfrbu_regs.pswbu.ctrl;
+ val &= ~soc_pm.sfrbu_regs.pswbu.ctrl;
+ val |= soc_pm.sfrbu_regs.pswbu.key;
writel(val, soc_pm.data.sfrbu + offset);
-
- /* Wait for update. */
- val = readl(soc_pm.data.sfrbu + offset);
- while (val & soc_pm.sfrbu_regs.pswbu.state)
- val = readl(soc_pm.data.sfrbu + offset);
}
static void at91_pm_suspend(suspend_state_t state)
{
if (soc_pm.data.mode == AT91_PM_BACKUP) {
- at91_pm_switch_ba_to_vbat();
+ at91_pm_switch_ba_to_auto();
cpu_suspend(0, at91_suspend_finish);