@@ -21,6 +21,7 @@
#include <asm/runlatch.h>
#include <asm/idle.h>
#include <asm/plpar_wrappers.h>
+#include <asm/rtas.h>
static struct cpuidle_driver pseries_idle_driver = {
.name = "pseries_idle",
@@ -87,6 +88,137 @@ static void check_and_cede_processor(void)
}
#define NR_DEDICATED_STATES 2 /* snooze, CEDE */
+/*
+ * XCEDE : Extended CEDE states discovered through the
+ * "ibm,get-systems-parameter" rtas-call with the token
+ * CEDE_LATENCY_TOKEN
+ */
+#define MAX_XCEDE_STATES 4
+#define XCEDE_LATENCY_RECORD_SIZE 10
+#define XCEDE_LATENCY_PARAM_MAX_LENGTH (2 + 2 + \
+ (MAX_XCEDE_STATES * XCEDE_LATENCY_RECORD_SIZE))
+
+/*
+ * Section 7.3.16 System Parameters Option of PAPR version 2.8.1 has a
+ * table with all the parameters to ibm,get-system-parameters.
+ * CEDE_LATENCY_TOKEN corresponds to the token value for Cede Latency
+ * Settings Information.
+ */
+#define CEDE_LATENCY_TOKEN 45
+
+/*
+ * If the platform supports the cede latency settings
+ * information system parameter it must provide the following
+ * information in the NULL terminated parameter string:
+ *
+ * a. The first byte is the length “N” of each cede
+ * latency setting record minus one (zero indicates a length
+ * of 1 byte).
+ *
+ * b. For each supported cede latency setting a cede latency
+ * setting record consisting of the first “N” bytes as per
+ * the following table.
+ *
+ * -----------------------------
+ * | Field | Field |
+ * | Name | Length |
+ * -----------------------------
+ * | Cede Latency | 1 Byte |
+ * | Specifier Value | |
+ * -----------------------------
+ * | Maximum wakeup | |
+ * | latency in | 8 Bytes|
+ * | tb-ticks | |
+ * -----------------------------
+ * | Responsive to | |
+ * | external | 1 Byte |
+ * | interrupts | |
+ * -----------------------------
+ *
+ * This version has cede latency record size = 10.
+ *
+ * The structure xcede_latency_payload represents a) and b) with
+ * xcede_latency_record representing the table in b).
+ *
+ * xcede_latency_parameter is what gets returned by
+ * ibm,get-systems-parameter rtas-call when made with
+ * CEDE_LATENCY_TOKEN.
+ *
+ * These structures are only used to represent the data sent obtained
+ * by the rtas-call. The data is in Big-Endian.
+ */
+struct xcede_latency_record {
+ u8 hint;
+ __be64 latency_ticks;
+ u8 wake_on_irqs;
+} __packed;
+
+struct xcede_latency_payload {
+ u8 record_size;
+ struct xcede_latency_record records[MAX_XCEDE_STATES];
+} __packed;
+
+struct xcede_latency_parameter {
+ __be16 payload_size;
+ struct xcede_latency_payload payload;
+ u8 null_char;
+} __packed;
+
+static unsigned int nr_xcede_records;
+static struct xcede_latency_parameter xcede_latency_parameter __initdata;
+
+static int __init parse_cede_parameters(void)
+{
+ int ret, i;
+ u16 payload_size;
+ u8 xcede_record_size;
+ u32 total_xcede_records_size;
+ struct xcede_latency_payload *payload;
+
+ memset(&xcede_latency_parameter, 0, sizeof(xcede_latency_parameter));
+
+ ret = rtas_call(rtas_token("ibm,get-system-parameter"), 3, 1,
+ NULL, CEDE_LATENCY_TOKEN, __pa(&xcede_latency_parameter),
+ sizeof(xcede_latency_parameter));
+
+ if (ret) {
+ pr_err("xcede: Error parsing CEDE_LATENCY_TOKEN\n");
+ return ret;
+ }
+
+ payload_size = be16_to_cpu(xcede_latency_parameter.payload_size);
+ payload = &xcede_latency_parameter.payload;
+
+ xcede_record_size = payload->record_size + 1;
+
+ if (xcede_record_size != XCEDE_LATENCY_RECORD_SIZE) {
+ pr_err("xcede : Expected record-size %d. Observed size %d.\n",
+ XCEDE_LATENCY_RECORD_SIZE, xcede_record_size);
+ return -EINVAL;
+ }
+
+ pr_info("xcede : xcede_record_size = %d\n", xcede_record_size);
+
+ /*
+ * Since the payload_length includes the last NULL byte and
+ * the xcede_record_size, the remaining bytes correspond to
+ * array of all cede_latency settings.
+ */
+ total_xcede_records_size = payload_size - 2;
+ nr_xcede_records = total_xcede_records_size / xcede_record_size;
+
+ for (i = 0; i < nr_xcede_records; i++) {
+ struct xcede_latency_record *record = &payload->records[i];
+ u8 hint = record->hint;
+ u8 wake_on_irqs = record->wake_on_irqs;
+ u64 latency_ticks = be64_to_cpu(record->latency_ticks);
+
+ pr_info("xcede : Record %d : hint = %u, latency = 0x%llx tb ticks, Wake-on-irq = %u\n",
+ i, hint, latency_ticks, wake_on_irqs);
+ }
+
+ return 0;
+}
u8 cede_latency_hint[NR_DEDICATED_STATES];
static int dedicated_cede_loop(struct cpuidle_device *dev,
@@ -218,6 +350,15 @@ static int pseries_cpuidle_driver_init(void)
return 0;
}
+static void __init parse_xcede_idle_states(void)
+{
+ if (parse_cede_parameters())
+ return;
+
+ pr_info("cpuidle : Skipping the %d Extended CEDE idle states\n",
+ nr_xcede_records);
+}
+
/*
* pseries_idle_probe()
* Choose state table for shared versus dedicated partition
@@ -239,6 +380,7 @@ static int pseries_idle_probe(void)
cpuidle_state_table = shared_states;
max_idle_state = ARRAY_SIZE(shared_states);
} else {
+ parse_xcede_idle_states();
cpuidle_state_table = dedicated_states;
max_idle_state = NR_DEDICATED_STATES;
}