feat(plat/imx8m): add system_reset2 implementation

Add imx_system_reset2 which extends existing SYSTEM_RESET. It provides
architectural reset definitions and vendor-specific resets.
By default warm reset is triggered.

Also refactor existing implementation of wdog reset, add details about
each flag used.

Change-Id: Ia7348c32c385f1c61f8085776e81dd1e38ddda5c
Signed-off-by: Igor Opaniuk <igor.opaniuk@foundries.io>

plat/imx/imx8m/imx8m_psci_common.c

@@ -152,19 +152,45 @@ void imx_get_sys_suspend_power_state(psci_power_state_t *req_state)
 		req_state->pwr_domain_state[i] = PLAT_STOP_OFF_STATE;
 }
 
-void __dead2 imx_system_reset(void)
+static void __dead2 imx_wdog_restart(bool external_reset)
 {
 	uintptr_t wdog_base = IMX_WDOG_BASE;
 	unsigned int val;
 
-	/* WDOG_B reset */
 	val = mmio_read_16(wdog_base);
-#ifdef IMX_WDOG_B_RESET
-	val = (val & 0x00FF) | WDOG_WCR_WDZST | WDOG_WCR_WDE |
-		WDOG_WCR_WDT | WDOG_WCR_SRS;
-#else
-	val = (val & 0x00FF) | WDOG_WCR_WDZST | WDOG_WCR_SRS;
-#endif
+	/*
+	 * Common watchdog init flags, for additional details check
+	 * 6.6.4.1 Watchdog Control Register (WDOGx_WCR)
+	 *
+	 * Initial bit selection:
+	 * WDOG_WCR_WDE - Enable the watchdog.
+	 *
+	 * 0x000E mask is used to keep previous values (that could be set
+	 * in SPL) of WDBG and WDE/WDT (both are write-one once-only bits).
+	 */
+	val = (val & 0x000E) | WDOG_WCR_WDE;
+	if (external_reset) {
+		/*
+		 * To assert WDOG_B (external reset) we have
+		 * to set WDA bit 0 (already set in previous step).
+		 * SRS bits are required to be set to 1 (no effect on the
+		 * system).
+		 */
+		val |= WDOG_WCR_SRS;
+	} else {
+		/*
+		 * To assert Software Reset Signal (internal reset) we have
+		 * to set SRS bit to 0 (already set in previous step).
+		 * SRE bit is required to be set to 1 when used in
+		 * conjunction with the Software Reset Signal before
+		 * SRS asserton, otherwise SRS bit will just automatically
+		 * reset to 1.
+		 *
+		 * Also we set WDA to 1 (no effect on system).
+		 */
+		val |= WDOG_WCR_SRE | WDOG_WCR_WDA;
+	}
+
 	mmio_write_16(wdog_base, val);
 
 	mmio_write_16(wdog_base + WDOG_WSR, 0x5555);
@@ -173,6 +199,27 @@ void __dead2 imx_system_reset(void)
 		;
 }
 
+void __dead2 imx_system_reset(void)
+{
+#ifdef IMX_WDOG_B_RESET
+	imx_wdog_restart(true);
+#else
+	imx_wdog_restart(false);
+#endif
+}
+
+int imx_system_reset2(int is_vendor, int reset_type, u_register_t cookie)
+{
+	imx_wdog_restart(false);
+
+	/*
+	 * imx_wdog_restart cannot return (as it's  a __dead function),
+	 * however imx_system_reset2 has to return some value according
+	 * to PSCI v1.1 spec.
+	 */
+	return 0;
+}
+
 void __dead2 imx_system_off(void)
 {
 	mmio_write_32(IMX_SNVS_BASE + SNVS_LPCR, SNVS_LPCR_SRTC_ENV |

plat/imx/imx8m/imx8mm/imx8mm_psci.c

@@ -28,6 +28,7 @@ static const plat_psci_ops_t imx_plat_psci_ops = {
 	.pwr_domain_pwr_down_wfi = imx_pwr_domain_pwr_down_wfi,
 	.get_sys_suspend_power_state = imx_get_sys_suspend_power_state,
 	.system_reset = imx_system_reset,
+	.system_reset2 = imx_system_reset2,
 	.system_off = imx_system_off,
 };
 

plat/imx/imx8m/imx8mq/imx8mq_psci.c

@@ -117,6 +117,7 @@ static const plat_psci_ops_t imx_plat_psci_ops = {
 	.pwr_domain_pwr_down_wfi = imx_pwr_domain_pwr_down_wfi,
 	.get_sys_suspend_power_state = imx_get_sys_suspend_power_state,
 	.system_reset = imx_system_reset,
+	.system_reset2 = imx_system_reset2,
 	.system_off = imx_system_off,
 };
 

plat/imx/imx8m/include/imx8m_psci.h

@@ -19,5 +19,6 @@ void imx_cpu_standby(plat_local_state_t cpu_state);
 void imx_domain_suspend(const psci_power_state_t *target_state);
 void imx_domain_suspend_finish(const psci_power_state_t *target_state);
 void __dead2 imx_pwr_domain_pwr_down_wfi(const psci_power_state_t *target_state);
+int imx_system_reset2(int is_vendor, int reset_type, u_register_t cookie);
 
 #endif /* IMX8M_PSCI_H */