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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * Author: Sudeep Holla <sudeep.holla@arm.com>4 * Copyright 2021 Arm Limited5 *6 * The PCC Address Space also referred as PCC Operation Region pertains to the7 * region of PCC subspace that succeeds the PCC signature. The PCC Operation8 * Region works in conjunction with the PCC Table(Platform Communications9 * Channel Table). PCC subspaces that are marked for use as PCC Operation10 * Regions must not be used as PCC subspaces for the standard ACPI features11 * such as CPPC, RASF, PDTT and MPST. These standard features must always use12 * the PCC Table instead.13 *14 * This driver sets up the PCC Address Space and installs an handler to enable15 * 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 respond28 * to PCC commands29 */30#define PCC_CMD_WAIT_RETRIES_NUM 500ULL31 32struct 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 40static struct acpi_pcc_info pcc_ctx;41 42static 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 49static acpi_status50acpi_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 96err_free_channel:97 pcc_mbox_free_channel(data->pcc_chan);98err_free_data:99 kfree(data);100 101 return ret;102}103 104static acpi_status105acpi_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 remote124 * processor could be much slower to reply. So add an arbitrary125 * 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 142void __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}154