[PATCH 2/9] bus: ti-sysc: Check for lost context in sysc_reinit_module()

Tony Lindgren
2021-09-21T10:01:37Z

There is no need to restore context if it was not lost. Let's add a new
function sysc_check_context() to check for lost context. To make use of it,
we need to save the sysconfig register status on enable and disable.

Signed-off-by: Tony Lindgren <tony@atomide.com>
---
drivers/bus/ti-sysc.c | 60 +++++++++++++++++++++++++++++++++++--------
1 file changed, 49 insertions(+), 11 deletions(-)

diff --git a/drivers/bus/ti-sysc.c b/drivers/bus/ti-sysc.c
--- a/drivers/bus/ti-sysc.c
+++ b/drivers/bus/ti-sysc.c
@@ -132,6 +132,7 @@ struct sysc {
struct ti_sysc_cookie cookie;
const char *name;
u32 revision;
+ u32 sysconfig;
unsigned int reserved:1;
unsigned int enabled:1;
unsigned int needs_resume:1;
@@ -1135,7 +1136,8 @@ static int sysc_enable_module(struct device *dev)
best_mode = fls(ddata->cfg.midlemodes) - 1;
if (best_mode > SYSC_IDLE_MASK) {
dev_err(dev, "%s: invalid midlemode\n", __func__);
- return -EINVAL;
+ error = -EINVAL;
+ goto save_context;
}

if (ddata->cfg.quirks & SYSC_QUIRK_SWSUP_MSTANDBY)
@@ -1153,13 +1155,16 @@ static int sysc_enable_module(struct device *dev)
sysc_write_sysconfig(ddata, reg);
}

- /* Flush posted write */
- sysc_read(ddata, ddata->offsets[SYSC_SYSCONFIG]);
+ error = 0;
+
+save_context:
+ /* Save context and flush posted write */
+ ddata->sysconfig = sysc_read(ddata, ddata->offsets[SYSC_SYSCONFIG]);

if (ddata->module_enable_quirk)
ddata->module_enable_quirk(ddata);

- return 0;
+ return error;
}

static int sysc_best_idle_mode(u32 idlemodes, u32 *best_mode)
@@ -1216,8 +1221,10 @@ static int sysc_disable_module(struct device *dev)
set_sidle:
/* Set SIDLE mode */
idlemodes = ddata->cfg.sidlemodes;
- if (!idlemodes || regbits->sidle_shift < 0)
- return 0;
+ if (!idlemodes || regbits->sidle_shift < 0) {
+ ret = 0;
+ goto save_context;
+ }

if (ddata->cfg.quirks & SYSC_QUIRK_SWSUP_SIDLE) {
best_mode = SYSC_IDLE_FORCE;
@@ -1225,7 +1232,8 @@ static int sysc_disable_module(struct device *dev)
ret = sysc_best_idle_mode(idlemodes, &best_mode);
if (ret) {
dev_err(dev, "%s: invalid sidlemode\n", __func__);
- return ret;
+ ret = -EINVAL;
+ goto save_context;
}
}

@@ -1236,10 +1244,13 @@ static int sysc_disable_module(struct device *dev)
reg |= 1 << regbits->autoidle_shift;
sysc_write_sysconfig(ddata, reg);

- /* Flush posted write */
- sysc_read(ddata, ddata->offsets[SYSC_SYSCONFIG]);
+ ret = 0;

- return 0;
+save_context:
+ /* Save context and flush posted write */
+ ddata->sysconfig = sysc_read(ddata, ddata->offsets[SYSC_SYSCONFIG]);
+
+ return ret;
}

static int __maybe_unused sysc_runtime_suspend_legacy(struct device *dev,
@@ -1377,13 +1388,40 @@ static int __maybe_unused sysc_runtime_resume(struct device *dev)
return error;
}

+/*
+ * Checks if device context was lost. Assumes the sysconfig register value
+ * after lost context is different from the configured value. Only works for
+ * enabled devices.
+ *
+ * Eventually we may want to also add support to using the context lost
+ * registers that some SoCs have.
+ */
+static int sysc_check_context(struct sysc *ddata)
+{
+ u32 reg;
+
+ if (!ddata->enabled)
+ return -ENODATA;
+
+ reg = sysc_read(ddata, ddata->offsets[SYSC_SYSCONFIG]);
+ if (reg == ddata->sysconfig)
+ return 0;
+
+ return -EACCES;
+}
+
static int sysc_reinit_module(struct sysc *ddata, bool leave_enabled)
{
struct device *dev = ddata->dev;
int error;

- /* Disable target module if it is enabled */
if (ddata->enabled) {
+ /* Nothing to do if enabled and context not lost */
+ error = sysc_check_context(ddata);
+ if (!error)
+ return 0;
+
+ /* Disable target module if it is enabled */
error = sysc_runtime_suspend(dev);
if (error)
dev_warn(dev, "reinit suspend failed: %i\n", error);
--
2.33.0