From: Vibhore Vardhan <vibhore@ti.com>

Introduce system suspend call that enables the ti_sci driver to support
low power mode when the user space issues a suspend to mem.

Also, write a ti_sci_prepare_system_suspend call to be used in the driver
suspend handler to allow the system to identify the low power mode being
entered and if necessary, send TISCI_MSG_PREPARE_SLEEP with information
about the mode being entered.

Sysfw version >= 10.00.04 support LPM_DM_MANAGED capability [2], where
Device Mgr firmware now manages which low power mode is chosen. Going
forward, this is the default configuration supported for TI AM62 family
of devices. The state chosen by the DM can be influenced by sending
constraints using the new LPM constraint APIs.

In case the firmware does not support LPM_DM_MANAGED mode, the mode
selection logic can be extended as needed. If no suspend-to-RAM modes
are supported, return without taking any action.

We're using "pm_suspend_target_state" to map the kernel's target suspend
state to SysFW low power mode. Make sure this is available only when
CONFIG_SUSPEND is enabled.

Suspend has to be split into two parts, ti_sci_suspend() will send
the prepare sleep message to prepare suspend. ti_sci_suspend_noirq()
sets IO isolation which needs to be done as late as possible to avoid
any issues. On resume this has to be done as early as possible.

Co-developed-by: Dave Gerlach <d-gerlach@ti.com>
Signed-off-by: Dave Gerlach <d-gerlach@ti.com>
Signed-off-by: Georgi Vlaev <g-vlaev@ti.com>
Signed-off-by: Dhruva Gole <d-gole@ti.com>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>
Signed-off-by: Vibhore Vardhan <vibhore@ti.com>
Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>
---
 drivers/firmware/ti_sci.c | 82 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 82 insertions(+)

diff --git a/drivers/firmware/ti_sci.c b/drivers/firmware/ti_sci.c
index d7a3990a6353..c6544cc12417 100644
--- a/drivers/firmware/ti_sci.c
+++ b/drivers/firmware/ti_sci.c
@@ -24,6 +24,7 @@
 #include <linux/slab.h>
 #include <linux/soc/ti/ti-msgmgr.h>
 #include <linux/soc/ti/ti_sci_protocol.h>
+#include <linux/suspend.h>
 #include <linux/sys_soc.h>
 #include <linux/reboot.h>
 
@@ -3608,6 +3609,84 @@ static int tisci_reboot_handler(struct sys_off_data *data)
 	return NOTIFY_BAD;
 }
 
+#ifdef CONFIG_SUSPEND
+static int ti_sci_prepare_system_suspend(struct ti_sci_info *info)
+{
+	u8 mode;
+
+	/*
+	 * Map and validate the target Linux suspend state to TISCI LPM.
+	 * Default is to let Device Manager select the low power mode.
+	 */
+	switch (pm_suspend_target_state) {
+	case PM_SUSPEND_MEM:
+		if (info->fw_caps & MSG_FLAG_CAPS_LPM_DM_MANAGED)
+			mode = TISCI_MSG_VALUE_SLEEP_MODE_DM_MANAGED;
+		else
+			/* DM Managed is not supported by the firmware. */
+			return -EOPNOTSUPP;
+		break;
+	default:
+		/*
+		 * Do not fail if we don't have action to take for a
+		 * specific suspend mode.
+		 */
+		return 0;
+	}
+
+	return ti_sci_cmd_prepare_sleep(&info->handle, mode, 0, 0, 0);
+}
+
+static int ti_sci_suspend(struct device *dev)
+{
+	struct ti_sci_info *info = dev_get_drvdata(dev);
+	int ret;
+
+	ret = ti_sci_prepare_system_suspend(info);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static int ti_sci_suspend_noirq(struct device *dev)
+{
+	struct ti_sci_info *info = dev_get_drvdata(dev);
+	int ret = 0;
+
+	ret = ti_sci_cmd_set_io_isolation(&info->handle, TISCI_MSG_VALUE_IO_ENABLE);
+	if (ret)
+		return ret;
+	dev_dbg(dev, "%s: set isolation: %d\n", __func__, ret);
+
+	return 0;
+}
+
+static int ti_sci_resume_noirq(struct device *dev)
+{
+	struct ti_sci_info *info = dev_get_drvdata(dev);
+	u32 source;
+	u64 time;
+	int ret = 0;
+
+	ret = ti_sci_cmd_set_io_isolation(&info->handle, TISCI_MSG_VALUE_IO_DISABLE);
+	if (ret)
+		return ret;
+	dev_dbg(dev, "%s: disable isolation: %d\n", __func__, ret);
+
+	ti_sci_msg_cmd_lpm_wake_reason(&info->handle, &source, &time);
+	dev_info(dev, "%s: wakeup source: 0x%X\n", __func__, source);
+
+	return 0;
+}
+
+static const struct dev_pm_ops ti_sci_pm_ops = {
+	.suspend = ti_sci_suspend,
+	.suspend_noirq = ti_sci_suspend_noirq,
+	.resume_noirq = ti_sci_resume_noirq,
+};
+#endif  /* CONFIG_SUSPEND */
+
 /* Description for K2G */
 static const struct ti_sci_desc ti_sci_pmmc_k2g_desc = {
 	.default_host_id = 2,
@@ -3777,6 +3856,9 @@ static struct platform_driver ti_sci_driver = {
 		   .name = "ti-sci",
 		   .of_match_table = of_match_ptr(ti_sci_of_match),
 		   .suppress_bind_attrs = true,
+#ifdef CONFIG_SUSPEND
+		   .pm = &ti_sci_pm_ops,
+#endif
 	},
 };
 module_platform_driver(ti_sci_driver);
-- 
2.45.2