Re: [PATCH v5 03/22] ACPI: CPPC: implement support for SystemIO registers

[Huang Rui <ray.huang@amd.com>]

On Fri, Dec 17, 2021 at 01:40:47AM +0800, Rafael J. Wysocki wrote:
> 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.

Will update it in V6.

> 
> > +                                        * 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.

OK.

> 
> > +                                       /* 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.

Fine, I will update this as well.

Thanks,
Ray

> 
> > +                       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;
> > --