ACPI, cpuidle: Clarify C-state description in sysfs

Add a new sysfs entry under cpuidle states. desc - can be used by driver to
communicate to userspace any specific information about the state.
This helps in identifying the exact hardware C-states behind the ACPI C-state
definition.

Idea is to export this through powertop, which will help to map the C-state
reported by powertop to actual hardware C-state.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

3 files changed, 24 insertions, 4 deletions

diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index 32003fdc91e8..baa389b908e2 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -945,11 +945,16 @@ static int acpi_processor_get_power_info_cst(struct acpi_processor *pr)
 				 * Otherwise, ignore this info and continue.
 				 */
 				cx.entry_method = ACPI_CSTATE_HALT;
+				snprintf(cx.desc, ACPI_CX_DESC_LEN, "ACPI HLT");
 			} else {
 				continue;
 			}
+		} else {
+			snprintf(cx.desc, ACPI_CX_DESC_LEN, "ACPI IOPORT 0x%x",
+				 cx.address);
 		}
 
+
 		obj = &(element->package.elements[2]);
 		if (obj->type != ACPI_TYPE_INTEGER)
 			continue;
@@ -1643,6 +1648,11 @@ static int acpi_processor_setup_cpuidle(struct acpi_processor *pr)
 		return -EINVAL;
 	}
 
+	for (i = 0; i < CPUIDLE_STATE_MAX; i++) {
+		dev->states[i].name[0] = '\0';
+		dev->states[i].desc[0] = '\0';
+	}
+
 	for (i = 1; i < ACPI_PROCESSOR_MAX_POWER && i <= max_cstate; i++) {
 		cx = &pr->power.states[i];
 		state = &dev->states[count];
@@ -1659,6 +1669,7 @@ static int acpi_processor_setup_cpuidle(struct acpi_processor *pr)
 		cpuidle_set_statedata(state, cx);
 
 		snprintf(state->name, CPUIDLE_NAME_LEN, "C%d", i);
+		strncpy(state->desc, cx->desc, CPUIDLE_DESC_LEN);
 		state->exit_latency = cx->latency;
 		state->target_residency = cx->latency * latency_factor;
 		state->power_usage = cx->power;
diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index 60f71e6345e3..d73663a52324 100644
--- a/drivers/cpuidle/cpuidle.c
+++ b/drivers/cpuidle/cpuidle.c
@@ -219,7 +219,8 @@ static void poll_idle_init(struct cpuidle_device *dev)
 
 	cpuidle_set_statedata(state, NULL);
 
-	snprintf(state->name, CPUIDLE_NAME_LEN, "C0 (poll idle)");
+	snprintf(state->name, CPUIDLE_NAME_LEN, "C0");
+	snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE");
 	state->exit_latency = 0;
 	state->target_residency = 0;
 	state->power_usage = -1;
diff --git a/drivers/cpuidle/sysfs.c b/drivers/cpuidle/sysfs.c
index 088ea74edd34..69102ca05685 100644
--- a/drivers/cpuidle/sysfs.c
+++ b/drivers/cpuidle/sysfs.c
@@ -218,16 +218,23 @@ static ssize_t show_state_##_name(struct cpuidle_state *state, char *buf) \
 	return sprintf(buf, "%u\n", state->_name);\
 }
 
-static ssize_t show_state_name(struct cpuidle_state *state, char *buf)
-{
-	return sprintf(buf, "%s\n", state->name);
+#define define_show_state_str_function(_name) \
+static ssize_t show_state_##_name(struct cpuidle_state *state, char *buf) \
+{ \
+	if (state->_name[0] == '\0')\
+		return sprintf(buf, "<null>\n");\
+	return sprintf(buf, "%s\n", state->_name);\
 }
 
 define_show_state_function(exit_latency)
 define_show_state_function(power_usage)
 define_show_state_function(usage)
 define_show_state_function(time)
+define_show_state_str_function(name)
+define_show_state_str_function(desc)
+
 define_one_state_ro(name, show_state_name);
+define_one_state_ro(desc, show_state_desc);
 define_one_state_ro(latency, show_state_exit_latency);
 define_one_state_ro(power, show_state_power_usage);
 define_one_state_ro(usage, show_state_usage);
@@ -235,6 +242,7 @@ define_one_state_ro(time, show_state_time);
 
 static struct attribute *cpuidle_state_default_attrs[] = {
 	&attr_name.attr,
+	&attr_desc.attr,
 	&attr_latency.attr,
 	&attr_power.attr,
 	&attr_usage.attr,