diff options
| -rw-r--r-- | drivers/acpi/cppc_acpi.c | 56 |
1 files changed, 55 insertions, 1 deletions
diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c index 8a0911a13599..8adac69dba3d 100644 --- a/drivers/acpi/cppc_acpi.c +++ b/drivers/acpi/cppc_acpi.c @@ -66,6 +66,7 @@ static u64 comm_base_addr; static int pcc_subspace_idx = -1; static bool pcc_channel_acquired; static ktime_t deadline; +static unsigned int pcc_mpar, pcc_mrtt; /* pcc mapped address + header size + offset within PCC subspace */ #define GET_PCC_VADDR(offs) (pcc_comm_addr + 0x8 + (offs)) @@ -85,6 +86,11 @@ static int check_pcc_chan(void) /* Retry in case the remote processor was too slow to catch up. */ while (!ktime_after(ktime_get(), next_deadline)) { + /* + * Per spec, prior to boot the PCC space wil be initialized by + * platform and should have set the command completion bit when + * PCC can be used by OSPM + */ if (readw_relaxed(&generic_comm_base->status) & PCC_CMD_COMPLETE) { ret = 0; break; @@ -104,6 +110,9 @@ static int send_pcc_cmd(u16 cmd) int ret = -EIO; struct acpi_pcct_shared_memory *generic_comm_base = (struct acpi_pcct_shared_memory *) pcc_comm_addr; + static ktime_t last_cmd_cmpl_time, last_mpar_reset; + static int mpar_count; + unsigned int time_delta; /* * For CMD_WRITE we know for a fact the caller should have checked @@ -115,6 +124,41 @@ static int send_pcc_cmd(u16 cmd) return ret; } + /* + * Handle the Minimum Request Turnaround Time(MRTT) + * "The minimum amount of time that OSPM must wait after the completion + * of a command before issuing the next command, in microseconds" + */ + if (pcc_mrtt) { + time_delta = ktime_us_delta(ktime_get(), last_cmd_cmpl_time); + if (pcc_mrtt > time_delta) + udelay(pcc_mrtt - time_delta); + } + + /* + * Handle the non-zero Maximum Periodic Access Rate(MPAR) + * "The maximum number of periodic requests that the subspace channel can + * support, reported in commands per minute. 0 indicates no limitation." + * + * This parameter should be ideally zero or large enough so that it can + * handle maximum number of requests that all the cores in the system can + * collectively generate. If it is not, we will follow the spec and just + * not send the request to the platform after hitting the MPAR limit in + * any 60s window + */ + if (pcc_mpar) { + if (mpar_count == 0) { + time_delta = ktime_ms_delta(ktime_get(), last_mpar_reset); + if (time_delta < 60 * MSEC_PER_SEC) { + pr_debug("PCC cmd not sent due to MPAR limit"); + return -EIO; + } + last_mpar_reset = ktime_get(); + mpar_count = pcc_mpar; + } + mpar_count--; + } + /* Write to the shared comm region. */ writew_relaxed(cmd, &generic_comm_base->command); @@ -135,9 +179,17 @@ static int send_pcc_cmd(u16 cmd) * because the actual write()s are done before coming here * and the next READ or WRITE will check if the channel * is busy/free at the entry of this call. + * + * If Minimum Request Turnaround Time is non-zero, we need + * to record the completion time of both READ and WRITE + * command for proper handling of MRTT, so we need to check + * for pcc_mrtt in addition to CMD_READ */ - if (cmd == CMD_READ) + if (cmd == CMD_READ || pcc_mrtt) { ret = check_pcc_chan(); + if (pcc_mrtt) + last_cmd_cmpl_time = ktime_get(); + } mbox_client_txdone(pcc_channel, ret); return ret; @@ -375,6 +427,8 @@ static int register_pcc_channel(int pcc_subspace_idx) */ usecs_lat = NUM_RETRIES * cppc_ss->latency; deadline = ns_to_ktime(usecs_lat * NSEC_PER_USEC); + pcc_mrtt = cppc_ss->min_turnaround_time; + pcc_mpar = cppc_ss->max_access_rate; pcc_comm_addr = acpi_os_ioremap(comm_base_addr, len); if (!pcc_comm_addr) { |