diff options
Diffstat (limited to 'drivers/cpuidle')
| -rw-r--r-- | drivers/cpuidle/cpuidle-pseries.c | 136 |
1 files changed, 135 insertions, 1 deletions
diff --git a/drivers/cpuidle/cpuidle-pseries.c b/drivers/cpuidle/cpuidle-pseries.c index 31c8e51162b2..abfc160c9837 100644 --- a/drivers/cpuidle/cpuidle-pseries.c +++ b/drivers/cpuidle/cpuidle-pseries.c @@ -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", @@ -86,8 +87,131 @@ 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 + */ + +/* + * 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 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; + +// Make space for 16 records, which "should be enough". +struct xcede_latency_payload { + u8 record_size; + struct xcede_latency_record records[16]; +} __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) +{ + struct xcede_latency_payload *payload; + u32 total_xcede_records_size; + u8 xcede_record_size; + u16 payload_size; + int ret, i; + + 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 != sizeof(struct xcede_latency_record)) { + pr_err("xcede: Expected record-size %lu. Observed size %u.\n", + sizeof(struct xcede_latency_record), xcede_record_size); + return -EINVAL; + } + + pr_info("xcede: xcede_record_size = %d\n", xcede_record_size); + + /* + * Since the payload_size 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]; + u64 latency_ticks = be64_to_cpu(record->latency_ticks); + u8 wake_on_irqs = record->wake_on_irqs; + u8 hint = record->hint; + + 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; +} + +#define NR_DEDICATED_STATES 2 /* snooze, CEDE */ static u8 cede_latency_hint[NR_DEDICATED_STATES]; static int dedicated_cede_loop(struct cpuidle_device *dev, @@ -219,6 +343,15 @@ 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 @@ -240,6 +373,7 @@ 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; } |