drivers/acpi/acpi_pcc.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Author: Sudeep Holla <sudeep.holla@arm.com>
   4  * Copyright 2021 Arm Limited
   5  *
   6  * The PCC Address Space also referred as PCC Operation Region pertains to the
   7  * region of PCC subspace that succeeds the PCC signature. The PCC Operation
   8  * Region works in conjunction with the PCC Table(Platform Communications
   9  * Channel Table). PCC subspaces that are marked for use as PCC Operation
  10  * Regions must not be used as PCC subspaces for the standard ACPI features
  11  * such as CPPC, RASF, PDTT and MPST. These standard features must always use
  12  * the PCC Table instead.
  13  *
  14  * This driver sets up the PCC Address Space and installs an handler to enable
  15  * handling of PCC OpRegion in the firmware.
  16  *
  17  */
  18 #include <linux/kernel.h>
  19 #include <linux/acpi.h>
  20 #include <linux/completion.h>
  21 #include <linux/idr.h>
  22 #include <linux/io.h>
  23
  24 #include <acpi/pcc.h>
  25
  26 /*
  27  * Arbitrary retries in case the remote processor is slow to respond
  28  * to PCC commands
  29  */
  30 #define PCC_CMD_WAIT_RETRIES_NUM        500ULL
  31
  32 struct pcc_data {
  33         struct pcc_mbox_chan *pcc_chan;
  34         void __iomem *pcc_comm_addr;
  35         struct completion done;
  36         struct mbox_client cl;
  37         struct acpi_pcc_info ctx;
  38 };
  39
  40 static struct acpi_pcc_info pcc_ctx;
  41
  42 static void pcc_rx_callback(struct mbox_client *cl, void *m)
  43 {
  44         struct pcc_data *data = container_of(cl, struct pcc_data, cl);
  45
  46         complete(&data->done);
  47 }
  48
  49 static acpi_status
  50 acpi_pcc_address_space_setup(acpi_handle region_handle, u32 function,
  51                              void *handler_context,  void **region_context)
  52 {
  53         struct pcc_data *data;
  54         struct acpi_pcc_info *ctx = handler_context;
  55         struct pcc_mbox_chan *pcc_chan;
  56         static acpi_status ret;
  57
  58         data = kzalloc(sizeof(*data), GFP_KERNEL);
  59         if (!data)
  60                 return AE_NO_MEMORY;
  61
  62         data->cl.rx_callback = pcc_rx_callback;
  63         data->cl.knows_txdone = true;
  64         data->ctx.length = ctx->length;
  65         data->ctx.subspace_id = ctx->subspace_id;
  66         data->ctx.internal_buffer = ctx->internal_buffer;
  67
  68         init_completion(&data->done);
  69         data->pcc_chan = pcc_mbox_request_channel(&data->cl, ctx->subspace_id);
  70         if (IS_ERR(data->pcc_chan)) {
  71                 pr_err("Failed to find PCC channel for subspace %d\n",
  72                        ctx->subspace_id);
  73                 ret = AE_NOT_FOUND;
  74                 goto err_free_data;
  75         }
  76
  77         pcc_chan = data->pcc_chan;
  78         if (!pcc_chan->mchan->mbox->txdone_irq) {
  79                 pr_err("This channel-%d does not support interrupt.\n",
  80                        ctx->subspace_id);
  81                 ret = AE_SUPPORT;
  82                 goto err_free_channel;
  83         }
  84         data->pcc_comm_addr = acpi_os_ioremap(pcc_chan->shmem_base_addr,
  85                                               pcc_chan->shmem_size);
  86         if (!data->pcc_comm_addr) {
  87                 pr_err("Failed to ioremap PCC comm region mem for %d\n",
  88                        ctx->subspace_id);
  89                 ret = AE_NO_MEMORY;
  90                 goto err_free_channel;
  91         }
  92
  93         *region_context = data;
  94         return AE_OK;
  95
  96 err_free_channel:
  97         pcc_mbox_free_channel(data->pcc_chan);
  98 err_free_data:
  99         kfree(data);
 100
 101         return ret;
 102 }
 103
 104 static acpi_status
 105 acpi_pcc_address_space_handler(u32 function, acpi_physical_address addr,
 106                                u32 bits, acpi_integer *value,
 107                                void *handler_context, void *region_context)
 108 {
 109         int ret;
 110         struct pcc_data *data = region_context;
 111         u64 usecs_lat;
 112
 113         reinit_completion(&data->done);
 114
 115         /* Write to Shared Memory */
 116         memcpy_toio(data->pcc_comm_addr, (void *)value, data->ctx.length);
 117
 118         ret = mbox_send_message(data->pcc_chan->mchan, NULL);
 119         if (ret < 0)
 120                 return AE_ERROR;
 121
 122         /*
 123          * pcc_chan->latency is just a Nominal value. In reality the remote
 124          * processor could be much slower to reply. So add an arbitrary
 125          * amount of wait on top of Nominal.
 126          */
 127         usecs_lat = PCC_CMD_WAIT_RETRIES_NUM * data->pcc_chan->latency;
 128         ret = wait_for_completion_timeout(&data->done,
 129                                                 usecs_to_jiffies(usecs_lat));
 130         if (ret == 0) {
 131                 pr_err("PCC command executed timeout!\n");
 132                 return AE_TIME;
 133         }
 134
 135         mbox_chan_txdone(data->pcc_chan->mchan, ret);
 136
 137         memcpy_fromio(value, data->pcc_comm_addr, data->ctx.length);
 138
 139         return AE_OK;
 140 }
 141
 142 void __init acpi_init_pcc(void)
 143 {
 144         acpi_status status;
 145
 146         status = acpi_install_address_space_handler(ACPI_ROOT_OBJECT,
 147                                                     ACPI_ADR_SPACE_PLATFORM_COMM,
 148                                                     &acpi_pcc_address_space_handler,
 149                                                     &acpi_pcc_address_space_setup,
 150                                                     &pcc_ctx);
 151         if (ACPI_FAILURE(status))
 152                 pr_alert("OperationRegion handler could not be installed\n");
 153 }