diff options
Diffstat (limited to 'drivers/acpi/pcc.c')
| -rw-r--r-- | drivers/acpi/pcc.c | 192 |
1 files changed, 192 insertions, 0 deletions
diff --git a/drivers/acpi/pcc.c b/drivers/acpi/pcc.c new file mode 100644 index 000000000000..328ca93faf3c --- /dev/null +++ b/drivers/acpi/pcc.c @@ -0,0 +1,192 @@ +/* + * Copyright (C) 2014 Linaro Ltd. + * Author: Ashwin Chaugule <ashwin.chaugule@linaro.org> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + */ + +#include <linux/acpi.h> +#include <linux/io.h> +#include <linux/uaccess.h> +#include <linux/init.h> +#include <linux/cpufreq.h> +#include <linux/delay.h> +#include <linux/ioctl.h> +#include <linux/vmalloc.h> + +#include <acpi/actbl.h> + +#define MAX_PCC_SUBSPACES 256 +#define PCCS_SS_SIG_MAGIC 0x50434300 +#define PCC_CMD_COMPLETE 0x1 +#define PCC_VERSION "0.1" + +struct pcc_ss_desc { + struct acpi_pcct_subspace *pcc_ss_ptr; + raw_spinlock_t lock; +}; + +/* Array of Type 0 PCC Subspace descriptors */ +struct pcc_ss_desc pcc_ss_arr[MAX_PCC_SUBSPACES]; + +/* Total number of subspaces detected in PCCT. */ +static int total_ss; + +/* + * PCC clients call this function to get a base address of their + * Communication channel + */ +int get_pcc_comm_channel(u32 ss_idx, u64 __iomem *addr, int *len) +{ + struct acpi_pcct_subspace *pcct_subspace = + pcc_ss_arr[ss_idx].pcc_ss_ptr; + + if (pcct_subspace) { + *addr = pcct_subspace->base_address; + *len = pcct_subspace->length; + } else + return -EINVAL; + + return 0; +} + +/* Send PCC cmd on behalf of this (subspace id) PCC client */ +u16 send_pcc_cmd(u8 cmd, u8 sci, u32 ss_idx, u64 __iomem *base_addr) +{ + struct acpi_pcct_subspace *pcct_subspace = + pcc_ss_arr[ss_idx].pcc_ss_ptr; + struct acpi_pcct_shared_memory *generic_comm_base = + (struct acpi_pcct_shared_memory *)base_addr; + struct acpi_generic_address doorbell; + u64 doorbell_preserve; + u64 doorbell_val; + u64 doorbell_write; + /* + * Min time in usec that OSPM is expected to wait + * before sending the next PCC cmd. + */ + u16 cmd_delay = pcct_subspace->min_turnaround_time; + + if (!generic_comm_base) { + pr_err("No Generic Communication Channel provided.\n"); + return -EINVAL; + } + + raw_spin_lock(&pcc_ss_arr[ss_idx].lock); + + /* Get doorbell details for this subspace. */ + doorbell = pcct_subspace->doorbell_register; + doorbell_preserve = pcct_subspace->preserve_mask; + doorbell_write = pcct_subspace->write_mask; + + /* Loop until CMD complete bit is set. For prev cmds. */ + while (!(ioread16(&generic_comm_base->status) & PCC_CMD_COMPLETE)) + udelay(cmd_delay); + + /* Write to the shared comm region. */ + iowrite16(cmd, &generic_comm_base->command); + + /* Write Subspace MAGIC value so platform can identify destination. */ + iowrite32((PCCS_SS_SIG_MAGIC | ss_idx), &generic_comm_base->signature); + + /* Flip CMD COMPLETE bit */ + iowrite16(0, &generic_comm_base->status); + + /* Sync notification from OSPM to Platform. */ + acpi_read(&doorbell_val, &doorbell); + acpi_write((doorbell_val & doorbell_preserve) | doorbell_write, + &doorbell); + + /* Wait for Platform to consume. */ + while (!(ioread16(&generic_comm_base->status) & PCC_CMD_COMPLETE)) + udelay(cmd_delay); + + raw_spin_unlock(&pcc_ss_arr[ss_idx].lock); + + return generic_comm_base->status; +} + +static int parse_pcc_subspace(struct acpi_subtable_header *header, + const unsigned long end) +{ + struct acpi_pcct_subspace *pcct_ss; + + if (total_ss <= MAX_PCC_SUBSPACES) { + pcct_ss = (struct acpi_pcct_subspace *) header; + + if (pcct_ss->header.type != ACPI_PCCT_TYPE_GENERIC_SUBSPACE) { + pr_err("Incorrect PCC Subspace type detected\n"); + return -EINVAL; + } + + pcc_ss_arr[total_ss].pcc_ss_ptr = pcct_ss; + raw_spin_lock_init(&pcc_ss_arr[total_ss].lock); + + total_ss++; + } else { + pr_err("No more space for PCC subspaces.\n"); + return -ENOSPC; + } + + return 0; +} + +static int __init pcc_probe(void) +{ + acpi_status status = AE_OK; + acpi_size pcct_tbl_header_size; + struct acpi_table_pcct *pcct_tbl; + + /* Search for PCCT */ + status = acpi_get_table_with_size(ACPI_SIG_PCCT, 0, + (struct acpi_table_header **)&pcct_tbl, + &pcct_tbl_header_size); + + if (ACPI_SUCCESS(status) && !pcct_tbl) { + pr_warn("PCCT header not found.\n"); + status = AE_NOT_FOUND; + goto out_err; + } + + status = acpi_table_parse_entries(ACPI_SIG_PCCT, + sizeof(struct acpi_table_pcct), + ACPI_PCCT_TYPE_GENERIC_SUBSPACE, + parse_pcc_subspace, MAX_PCC_SUBSPACES); + + if (ACPI_SUCCESS(status)) + pr_err("Error parsing PCC subspaces from PCCT\n"); + + pr_info("Detected %d PCC Subspaces\n", total_ss); + +out_err: + return ACPI_SUCCESS(status) ? 1 : 0; +} + +static int __init pcc_init(void) +{ + int ret; + + if (acpi_disabled) + return -ENODEV; + + /* Check if PCC support is available. */ + ret = pcc_probe(); + + if (ret) { + pr_debug("PCC probe failed.\n"); + return -EINVAL; + } + + return ret; +} + +device_initcall(pcc_init); |