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 struct pcc_data {
  27         struct pcc_mbox_chan *pcc_chan;
  28         void __iomem *pcc_comm_addr;
  29         struct completion done;
  30         struct mbox_client cl;
  31         struct acpi_pcc_info ctx;
  32 };
  33
  34 static struct acpi_pcc_info pcc_ctx;
  35
  36 static void pcc_rx_callback(struct mbox_client *cl, void *m)
  37 {
  38         struct pcc_data *data = container_of(cl, struct pcc_data, cl);
  39
  40         complete(&data->done);
  41 }
  42
  43 static acpi_status
  44 acpi_pcc_address_space_setup(acpi_handle region_handle, u32 function,
  45                              void *handler_context,  void **region_context)
  46 {
  47         struct pcc_data *data;
  48         struct acpi_pcc_info *ctx = handler_context;
  49         struct pcc_mbox_chan *pcc_chan;
  50
  51         data = kzalloc(sizeof(*data), GFP_KERNEL);
  52         if (!data)
  53                 return AE_NO_MEMORY;
  54
  55         data->cl.rx_callback = pcc_rx_callback;
  56         data->cl.knows_txdone = true;
  57         data->ctx.length = ctx->length;
  58         data->ctx.subspace_id = ctx->subspace_id;
  59         data->ctx.internal_buffer = ctx->internal_buffer;
  60
  61         init_completion(&data->done);
  62         data->pcc_chan = pcc_mbox_request_channel(&data->cl, ctx->subspace_id);
  63         if (IS_ERR(data->pcc_chan)) {
  64                 pr_err("Failed to find PCC channel for subspace %d\n",
  65                        ctx->subspace_id);
  66                 return AE_NOT_FOUND;
  67         }
  68
  69         pcc_chan = data->pcc_chan;
  70         data->pcc_comm_addr = acpi_os_ioremap(pcc_chan->shmem_base_addr,
  71                                               pcc_chan->shmem_size);
  72         if (!data->pcc_comm_addr) {
  73                 pr_err("Failed to ioremap PCC comm region mem for %d\n",
  74                        ctx->subspace_id);
  75                 return AE_NO_MEMORY;
  76         }
  77
  78         *region_context = data;
  79         return AE_OK;
  80 }
  81
  82 static acpi_status
  83 acpi_pcc_address_space_handler(u32 function, acpi_physical_address addr,
  84                                u32 bits, acpi_integer *value,
  85                                void *handler_context, void *region_context)
  86 {
  87         int ret;
  88         struct pcc_data *data = region_context;
  89
  90         reinit_completion(&data->done);
  91
  92         /* Write to Shared Memory */
  93         memcpy_toio(data->pcc_comm_addr, (void *)value, data->ctx.length);
  94
  95         ret = mbox_send_message(data->pcc_chan->mchan, NULL);
  96         if (ret < 0)
  97                 return AE_ERROR;
  98
  99         if (data->pcc_chan->mchan->mbox->txdone_irq)
 100                 wait_for_completion(&data->done);
 101
 102         mbox_client_txdone(data->pcc_chan->mchan, ret);
 103
 104         memcpy_fromio(value, data->pcc_comm_addr, data->ctx.length);
 105
 106         return AE_OK;
 107 }
 108
 109 void __init acpi_init_pcc(void)
 110 {
 111         acpi_status status;
 112
 113         status = acpi_install_address_space_handler(ACPI_ROOT_OBJECT,
 114                                                     ACPI_ADR_SPACE_PLATFORM_COMM,
 115                                                     &acpi_pcc_address_space_handler,
 116                                                     &acpi_pcc_address_space_setup,
 117                                                     &pcc_ctx);
 118         if (ACPI_FAILURE(status))
 119                 pr_alert("OperationRegion handler could not be installed\n");
 120 }