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SubjectRe: [PATCH v5 03/22] ACPI: CPPC: implement support for SystemIO registers
On Tue, Nov 30, 2021 at 1:37 PM Huang Rui <ray.huang@amd.com> wrote:
>
> From: Steven Noonan <steven@valvesoftware.com>
>
> According to the ACPI v6.2 (and later) specification, SystemIO can be
> used for _CPC registers. This teaches cppc_acpi how to handle such
> registers.
>
> This patch was tested using the amd_pstate driver on my Zephyrus G15
> (model GA503QS) using the current version 410 BIOS, which uses
> a SystemIO register for the HighestPerformance element in _CPC.
>
> Signed-off-by: Steven Noonan <steven@valvesoftware.com>
> Signed-off-by: Huang Rui <ray.huang@amd.com>
> ---
> drivers/acpi/cppc_acpi.c | 46 +++++++++++++++++++++++++++++++++++++---
> 1 file changed, 43 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
> index a85c351589be..ca62c3dc9899 100644
> --- a/drivers/acpi/cppc_acpi.c
> +++ b/drivers/acpi/cppc_acpi.c
> @@ -746,9 +746,24 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr)
> goto out_free;
> cpc_ptr->cpc_regs[i-2].sys_mem_vaddr = addr;
> }
> + } else if (gas_t->space_id == ACPI_ADR_SPACE_SYSTEM_IO) {
> + if (gas_t->access_width < 1 || gas_t->access_width > 3) {
> + /* 1 = 8-bit, 2 = 16-bit, and 3 = 32-bit. SystemIO doesn't

The comment format is not in agreement with the kernel coding style.

> + * implement 64-bit registers.
> + */
> + pr_debug("Invalid access width %d for SystemIO register\n",
> + gas_t->access_width);
> + goto out_free;
> + }
> + if (gas_t->address & ~0xFFFFULL) {

It would be good to define a symbol for this mask and use it here
instead of the raw vaue.

> + /* SystemIO registers use 16-bit integer addresses */
> + pr_debug("Invalid IO port %llu for SystemIO register\n",
> + gas_t->address);
> + goto out_free;
> + }
> } else {
> if (gas_t->space_id != ACPI_ADR_SPACE_FIXED_HARDWARE || !cpc_ffh_supported()) {
> - /* Support only PCC ,SYS MEM and FFH type regs */
> + /* Support only PCC, SystemMemory, SystemIO, and FFH type regs. */
> pr_debug("Unsupported register type: %d\n", gas_t->space_id);
> goto out_free;
> }
> @@ -923,7 +938,20 @@ static int cpc_read(int cpu, struct cpc_register_resource *reg_res, u64 *val)
> }
>
> *val = 0;
> - if (reg->space_id == ACPI_ADR_SPACE_PLATFORM_COMM && pcc_ss_id >= 0)
> +
> + if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_IO) {
> + u32 width = 8 << (reg->access_width - 1);
> + acpi_status status;
> +
> + status = acpi_os_read_port((acpi_io_address)reg->address, (u32 *)val, width);
> +
> + if (status != AE_OK) {

Please use ACPI_FAILURE() here and in the analogous check and below.

> + pr_debug("Error: Failed to read SystemIO port %llx\n", reg->address);
> + return -EFAULT;
> + }
> +
> + return 0;
> + } else if (reg->space_id == ACPI_ADR_SPACE_PLATFORM_COMM && pcc_ss_id >= 0)
> vaddr = GET_PCC_VADDR(reg->address, pcc_ss_id);
> else if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY)
> vaddr = reg_res->sys_mem_vaddr;
> @@ -962,7 +990,19 @@ static int cpc_write(int cpu, struct cpc_register_resource *reg_res, u64 val)
> int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpu);
> struct cpc_reg *reg = &reg_res->cpc_entry.reg;
>
> - if (reg->space_id == ACPI_ADR_SPACE_PLATFORM_COMM && pcc_ss_id >= 0)
> + if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_IO) {
> + u32 width = 8 << (reg->access_width - 1);
> + acpi_status status;
> +
> + status = acpi_os_write_port((acpi_io_address)reg->address, (u32)val, width);
> +
> + if (status != AE_OK) {
> + pr_debug("Error: Failed to write SystemIO port %llx\n", reg->address);
> + return -EFAULT;
> + }
> +
> + return 0;
> + } else if (reg->space_id == ACPI_ADR_SPACE_PLATFORM_COMM && pcc_ss_id >= 0)
> vaddr = GET_PCC_VADDR(reg->address, pcc_ss_id);
> else if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY)
> vaddr = reg_res->sys_mem_vaddr;
> --

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