diff options
Diffstat (limited to 'drivers/acpi/acpi_pcc.c')
| -rw-r--r-- | drivers/acpi/acpi_pcc.c | 153 |
1 files changed, 153 insertions, 0 deletions
diff --git a/drivers/acpi/acpi_pcc.c b/drivers/acpi/acpi_pcc.c new file mode 100644 index 0000000000..07a034a53a --- /dev/null +++ b/drivers/acpi/acpi_pcc.c @@ -0,0 +1,153 @@ +// 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"); +} |