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// SPDX-License-Identifier: GPL-2.0-only
/*
* Author: Sudeep Holla <sudeep.holla@arm.com>
* Copyright 2021 Arm Limited
*
* The PCC Address Space also referred as PCC Operation Region pertains to the
* region of PCC subspace that succeeds the PCC signature. The PCC Operation
* Region works in conjunction with the PCC Table(Platform Communications
* Channel Table). PCC subspaces that are marked for use as PCC Operation
* Regions must not be used as PCC subspaces for the standard ACPI features
* such as CPPC, RASF, PDTT and MPST. These standard features must always use
* the PCC Table instead.
*
* This driver sets up the PCC Address Space and installs an handler to enable
* handling of PCC OpRegion in the firmware.
*
*/
#include <linux/kernel.h>
#include <linux/acpi.h>
#include <linux/completion.h>
#include <linux/idr.h>
#include <linux/io.h>
#include <acpi/pcc.h>
/*
* Arbitrary retries in case the remote processor is slow to respond
* to PCC commands
*/
#define PCC_CMD_WAIT_RETRIES_NUM 500ULL
struct pcc_data {
struct pcc_mbox_chan *pcc_chan;
void __iomem *pcc_comm_addr;
struct completion done;
struct mbox_client cl;
struct acpi_pcc_info ctx;
};
static struct acpi_pcc_info pcc_ctx;
static void pcc_rx_callback(struct mbox_client *cl, void *m)
{
struct pcc_data *data = container_of(cl, struct pcc_data, cl);
complete(&data->done);
}
static acpi_status
acpi_pcc_address_space_setup(acpi_handle region_handle, u32 function,
void *handler_context, void **region_context)
{
struct pcc_data *data;
struct acpi_pcc_info *ctx = handler_context;
struct pcc_mbox_chan *pcc_chan;
static acpi_status ret;
data = kzalloc(sizeof(*data), GFP_KERNEL);
if (!data)
return AE_NO_MEMORY;
data->cl.rx_callback = pcc_rx_callback;
data->cl.knows_txdone = true;
data->ctx.length = ctx->length;
data->ctx.subspace_id = ctx->subspace_id;
data->ctx.internal_buffer = ctx->internal_buffer;
init_completion(&data->done);
data->pcc_chan = pcc_mbox_request_channel(&data->cl, ctx->subspace_id);
if (IS_ERR(data->pcc_chan)) {
pr_err("Failed to find PCC channel for subspace %d\n",
ctx->subspace_id);
ret = AE_NOT_FOUND;
goto err_free_data;
}
pcc_chan = data->pcc_chan;
if (!pcc_chan->mchan->mbox->txdone_irq) {
pr_err("This channel-%d does not support interrupt.\n",
ctx->subspace_id);
ret = AE_SUPPORT;
goto err_free_channel;
}
data->pcc_comm_addr = acpi_os_ioremap(pcc_chan->shmem_base_addr,
pcc_chan->shmem_size);
if (!data->pcc_comm_addr) {
pr_err("Failed to ioremap PCC comm region mem for %d\n",
ctx->subspace_id);
ret = AE_NO_MEMORY;
goto err_free_channel;
}
*region_context = data;
return AE_OK;
err_free_channel:
pcc_mbox_free_channel(data->pcc_chan);
err_free_data:
kfree(data);
return ret;
}
static acpi_status
acpi_pcc_address_space_handler(u32 function, acpi_physical_address addr,
u32 bits, acpi_integer *value,
void *handler_context, void *region_context)
{
int ret;
struct pcc_data *data = region_context;
u64 usecs_lat;
reinit_completion(&data->done);
/* Write to Shared Memory */
memcpy_toio(data->pcc_comm_addr, (void *)value, data->ctx.length);
ret = mbox_send_message(data->pcc_chan->mchan, NULL);
if (ret < 0)
return AE_ERROR;
/*
* pcc_chan->latency is just a Nominal value. In reality the remote
* processor could be much slower to reply. So add an arbitrary
* amount of wait on top of Nominal.
*/
usecs_lat = PCC_CMD_WAIT_RETRIES_NUM * data->pcc_chan->latency;
ret = wait_for_completion_timeout(&data->done,
usecs_to_jiffies(usecs_lat));
if (ret == 0) {
pr_err("PCC command executed timeout!\n");
return AE_TIME;
}
mbox_chan_txdone(data->pcc_chan->mchan, ret);
memcpy_fromio(value, data->pcc_comm_addr, data->ctx.length);
return AE_OK;
}
void __init acpi_init_pcc(void)
{
acpi_status status;
status = acpi_install_address_space_handler(ACPI_ROOT_OBJECT,
ACPI_ADR_SPACE_PLATFORM_COMM,
&acpi_pcc_address_space_handler,
&acpi_pcc_address_space_setup,
&pcc_ctx);
if (ACPI_FAILURE(status))
pr_alert("OperationRegion handler could not be installed\n");
}
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