drivers/acpi/riscv/cpuidle.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2024, Ventana Micro Systems Inc
   4  *      Author: Sunil V L <sunilvl@ventanamicro.com>
   5  *
   6  */
   7
   8 #include <linux/acpi.h>
   9 #include <acpi/processor.h>
  10 #include <linux/cpu_pm.h>
  11 #include <linux/cpuidle.h>
  12 #include <linux/suspend.h>
  13 #include <asm/cpuidle.h>
  14 #include <asm/sbi.h>
  15 #include <asm/suspend.h>
  16
  17 #define RISCV_FFH_LPI_TYPE_MASK GENMASK_ULL(63, 60)
  18 #define RISCV_FFH_LPI_RSVD_MASK GENMASK_ULL(59, 32)
  19
  20 #define RISCV_FFH_LPI_TYPE_SBI  BIT_ULL(60)
  21
  22 static int acpi_cpu_init_idle(unsigned int cpu)
  23 {
  24         int i;
  25         struct acpi_lpi_state *lpi;
  26         struct acpi_processor *pr = per_cpu(processors, cpu);
  27
  28         if (unlikely(!pr || !pr->flags.has_lpi))
  29                 return -EINVAL;
  30
  31         if (!riscv_sbi_hsm_is_supported())
  32                 return -ENODEV;
  33
  34         if (pr->power.count <= 1)
  35                 return -ENODEV;
  36
  37         for (i = 1; i < pr->power.count; i++) {
  38                 u32 state;
  39
  40                 lpi = &pr->power.lpi_states[i];
  41
  42                 /*
  43                  * Validate Entry Method as per FFH spec.
  44                  * bits[63:60] should be 0x1
  45                  * bits[59:32] should be 0x0
  46                  * bits[31:0] represent a SBI power_state
  47                  */
  48                 if (((lpi->address & RISCV_FFH_LPI_TYPE_MASK) != RISCV_FFH_LPI_TYPE_SBI) ||
  49                     (lpi->address & RISCV_FFH_LPI_RSVD_MASK)) {
  50                         pr_warn("Invalid LPI entry method %#llx\n", lpi->address);
  51                         return -EINVAL;
  52                 }
  53
  54                 state = lpi->address;
  55                 if (!riscv_sbi_suspend_state_is_valid(state)) {
  56                         pr_warn("Invalid SBI power state %#x\n", state);
  57                         return -EINVAL;
  58                 }
  59         }
  60
  61         return 0;
  62 }
  63
  64 int acpi_processor_ffh_lpi_probe(unsigned int cpu)
  65 {
  66         return acpi_cpu_init_idle(cpu);
  67 }
  68
  69 int acpi_processor_ffh_lpi_enter(struct acpi_lpi_state *lpi)
  70 {
  71         u32 state = lpi->address;
  72
  73         if (state & SBI_HSM_SUSP_NON_RET_BIT)
  74                 return CPU_PM_CPU_IDLE_ENTER_PARAM(riscv_sbi_hart_suspend,
  75                                                    lpi->index,
  76                                                    state);
  77         else
  78                 return CPU_PM_CPU_IDLE_ENTER_RETENTION_PARAM(riscv_sbi_hart_suspend,
  79                                                              lpi->index,
  80                                                              state);
  81 }