soc: ti: wkup_m3_ipc: Add support for IO Isolation

AM43xx support isolation of the IOs so that control is taken
from the peripheral they are connected to and overridden by values
present in the CTRL_CONF_* registers for the pad in the control module.

The actual toggling happens from the wkup_m3, so use a DT property from
the wkup_m3_ipc node to allow the PM code to communicate the necessity
for placing the IOs into isolation to the firmware.

Signed-off-by: Dave Gerlach <d-gerlach@ti.com>
Signed-off-by: Keerthy <j-keerthy@ti.com>
Signed-off-by: Drew Fustini <dfustini@baylibre.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
Link: https://lore.kernel.org/r/20220414192722.2978837-3-dfustini@baylibre.com

Author: dgerlach

drivers/soc/ti/wkup_m3_ipc.c

@@ -46,6 +46,8 @@
 #define IPC_VTT_STAT_MASK		(0x1 << 3)
 #define IPC_VTT_GPIO_PIN_SHIFT		(0x4)
 #define IPC_VTT_GPIO_PIN_MASK		(0x3f << 4)
+#define IPC_IO_ISOLATION_STAT_SHIFT	(10)
+#define IPC_IO_ISOLATION_STAT_MASK	(0x1 << 10)
 
 #define M3_STATE_UNKNOWN		0
 #define M3_STATE_RESET			1
@@ -228,6 +230,11 @@ static void wkup_m3_set_vtt_gpio(struct wkup_m3_ipc *m3_ipc, int gpio)
 			    (gpio << IPC_VTT_GPIO_PIN_SHIFT);
 }
 
+static void wkup_m3_set_io_isolation(struct wkup_m3_ipc *m3_ipc)
+{
+	m3_ipc->isolation_conf = (1 << IPC_IO_ISOLATION_STAT_SHIFT);
+}
+
 /* Public functions */
 /**
  * wkup_m3_set_mem_type - Pass wkup_m3 which type of memory is in use
@@ -308,8 +315,8 @@ static int wkup_m3_prepare_low_power(struct wkup_m3_ipc *m3_ipc, int state)
 	wkup_m3_ctrl_ipc_write(m3_ipc, m3_ipc->resume_addr, 0);
 	wkup_m3_ctrl_ipc_write(m3_ipc, m3_power_state, 1);
 	wkup_m3_ctrl_ipc_write(m3_ipc, m3_ipc->mem_type |
-			       m3_ipc->vtt_conf, 4);
-
+			       m3_ipc->vtt_conf |
+			       m3_ipc->isolation_conf, 4);
 	wkup_m3_ctrl_ipc_write(m3_ipc, DS_IPC_DEFAULT, 2);
 	wkup_m3_ctrl_ipc_write(m3_ipc, DS_IPC_DEFAULT, 3);
 	wkup_m3_ctrl_ipc_write(m3_ipc, DS_IPC_DEFAULT, 5);
@@ -516,6 +523,9 @@ static int wkup_m3_ipc_probe(struct platform_device *pdev)
 			dev_warn(dev, "Invalid VTT GPIO(%d) pin\n", temp);
 	}
 
+	if (of_find_property(np, "ti,set-io-isolation", NULL))
+		wkup_m3_set_io_isolation(m3_ipc);
+
 	/*
 	 * Wait for firmware loading completion in a thread so we
 	 * can boot the wkup_m3 as soon as it's ready without holding

include/linux/wkup_m3_ipc.h

@@ -34,6 +34,7 @@ struct wkup_m3_ipc {
 	int mem_type;
 	unsigned long resume_addr;
 	int vtt_conf;
+	int isolation_conf;
 	int state;
 
 	struct completion sync_complete;