[PATCH 11/11] soc: ti: wkup_m3_ipc: Add debug option to halt m3 in suspend

[Drew Fustini]

From: Dave Gerlach <d-gerlach at ti.com>

Add a debugfs option to allow configurable halting of the wkup_m3
during suspend at the last possible point before low power mode entry.
This condition can only be resolved through JTAG and advancing beyond
the while loop in a8_lp_ds0_handler. Although this hangs the system it
forces the system to remain active once it has been entirely configured
for low power mode entry, allowing for register inspection through JTAG
to help in debugging transition errors.

Halt mode can be set using the enable_off_mode entry under wkup_m3_ipc
in the debugfs.

Suggested-by: Brad Griffis <bgriffis at ti.com>
Signed-off-by: Dave Gerlach <d-gerlach at ti.com>
[dfustini: resolve trivial line conflicts]
Signed-off-by: Drew Fustini <dfustini at baylibre.com>
---
 drivers/soc/ti/wkup_m3_ipc.c | 78 +++++++++++++++++++++++++++++++++++-
 include/linux/wkup_m3_ipc.h  |  2 +
 2 files changed, 79 insertions(+), 1 deletion(-)

diff --git a/drivers/soc/ti/wkup_m3_ipc.c b/drivers/soc/ti/wkup_m3_ipc.c
index 5a1722c3bf1a..244bce3f52e8 100644
--- a/drivers/soc/ti/wkup_m3_ipc.c
+++ b/drivers/soc/ti/wkup_m3_ipc.c
@@ -7,6 +7,7 @@
  * Dave Gerlach <d-gerlach at ti.com>
  */
 
+#include <linux/debugfs.h>
 #include <linux/err.h>
 #include <linux/firmware.h>
 #include <linux/kernel.h>
@@ -50,6 +51,9 @@
 #define IPC_IO_ISOLATION_STAT_SHIFT	(10)
 #define IPC_IO_ISOLATION_STAT_MASK	(0x1 << 10)
 
+#define IPC_DBG_HALT_SHIFT		(11)
+#define IPC_DBG_HALT_MASK		(0x1 << 11)
+
 #define M3_STATE_UNKNOWN		0
 #define M3_STATE_RESET			1
 #define M3_STATE_INITED			2
@@ -137,6 +141,73 @@ static void wkup_m3_scale_data_fw_cb(const struct firmware *fw, void *context)
 	release_firmware(fw);
 };
 
+#ifdef CONFIG_DEBUG_FS
+static void wkup_m3_set_halt_late(bool enabled)
+{
+	if (enabled)
+		m3_ipc_state->halt = (1 << IPC_DBG_HALT_SHIFT);
+	else
+		m3_ipc_state->halt = 0;
+}
+
+static int option_get(void *data, u64 *val)
+{
+	u32 *option = data;
+
+	*val = *option;
+
+	return 0;
+}
+
+static int option_set(void *data, u64 val)
+{
+	u32 *option = data;
+
+	*option = val;
+
+	if (option == &m3_ipc_state->halt) {
+		if (val)
+			wkup_m3_set_halt_late(true);
+		else
+			wkup_m3_set_halt_late(false);
+	}
+
+	return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(wkup_m3_ipc_option_fops, option_get, option_set,
+			"%llu\n");
+
+static int wkup_m3_ipc_dbg_init(struct wkup_m3_ipc *m3_ipc)
+{
+	m3_ipc->dbg_path = debugfs_create_dir("wkup_m3_ipc", NULL);
+
+	if (!m3_ipc->dbg_path)
+		return -EINVAL;
+
+	(void)debugfs_create_file("enable_late_halt", 0644,
+				  m3_ipc->dbg_path,
+				  &m3_ipc->halt,
+				  &wkup_m3_ipc_option_fops);
+
+	return 0;
+}
+
+static inline void wkup_m3_ipc_dbg_destroy(struct wkup_m3_ipc *m3_ipc)
+{
+	debugfs_remove_recursive(m3_ipc->dbg_path);
+}
+#else
+static inline int wkup_m3_ipc_dbg_init(struct wkup_m3_ipc *m3_ipc)
+{
+	return 0;
+}
+
+static inline void wkup_m3_ipc_dbg_destroy(struct wkup_m3_ipc *m3_ipc)
+{
+}
+#endif /* CONFIG_DEBUG_FS */
+
 static int wkup_m3_init_scale_data(struct wkup_m3_ipc *m3_ipc,
 				   struct device *dev)
 {
@@ -402,7 +473,8 @@ static int wkup_m3_prepare_low_power(struct wkup_m3_ipc *m3_ipc, int state)
 	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 |
-			       m3_ipc->isolation_conf, 4);
+			       m3_ipc->isolation_conf |
+			       m3_ipc->halt, 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, 6);
@@ -634,6 +706,8 @@ static int wkup_m3_ipc_probe(struct platform_device *pdev)
 		goto err_put_rproc;
 	}
 
+	wkup_m3_ipc_dbg_init(m3_ipc);
+
 	return 0;
 
 err_put_rproc:
@@ -645,6 +719,8 @@ static int wkup_m3_ipc_probe(struct platform_device *pdev)
 
 static int wkup_m3_ipc_remove(struct platform_device *pdev)
 {
+	wkup_m3_ipc_dbg_destroy(m3_ipc_state);
+
 	mbox_free_channel(m3_ipc_state->mbox);
 
 	rproc_shutdown(m3_ipc_state->rproc);
diff --git a/include/linux/wkup_m3_ipc.h b/include/linux/wkup_m3_ipc.h
index fef0fac60f8c..26d1eb058fa3 100644
--- a/include/linux/wkup_m3_ipc.h
+++ b/include/linux/wkup_m3_ipc.h
@@ -36,6 +36,7 @@ struct wkup_m3_ipc {
 	int vtt_conf;
 	int isolation_conf;
 	int state;
+	u32 halt;
 
 	unsigned long volt_scale_offsets;
 	const char *sd_fw_name;
@@ -46,6 +47,7 @@ struct wkup_m3_ipc {
 
 	struct wkup_m3_ipc_ops *ops;
 	int is_rtc_only;
+	struct dentry *dbg_path;
 };
 
 struct wkup_m3_wakeup_src {
-- 
2.32.0