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Date: Sat, 20 Aug 2016 02:49:02 +0200
From: "Rafael J. Wysocki" <rjw@...ysocki.net>
To: Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
Cc: mingo@...hat.com, tglx@...utronix.de, hpa@...or.com,
peterz@...radead.org, x86@...nel.org, bp@...e.de,
sudeep.holla@....com, ak@...ux.intel.com,
linux-acpi@...r.kernel.org, linux-pm@...r.kernel.org,
alexey.klimov@....com, viresh.kumar@...aro.org,
akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
lenb@...nel.org, tim.c.chen@...ux.intel.com,
paul.gortmaker@...driver.com, jpoimboe@...hat.com,
mcgrof@...nel.org, jgross@...e.com, robert.moore@...el.com,
dvyukov@...gle.com, jeyu@...hat.com
Subject: Re: [PATCH 07/11] acpi: cppc: Add support for function fixed hardware address
On Thursday, August 18, 2016 03:36:48 PM Srinivas Pandruvada wrote:
> The CPPC registers can also be accessed via function fixed hardware
> addresses in X86. Add support by modifying cpc_read and cpc_write
> to be able to read/write MSRs on x86 platform. Also with this change,
> acpi_cppc_processor_probe doesn't bail out if space id is not equal to
> PCC or memory address space.
>
> Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
> ---
> drivers/acpi/cppc_acpi.c | 77 +++++++++++++++++++++++++++++++++++++++++-------
> 1 file changed, 66 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
> index 34209f5..939fb5c 100644
> --- a/drivers/acpi/cppc_acpi.c
> +++ b/drivers/acpi/cppc_acpi.c
> @@ -42,6 +42,10 @@
> #include <linux/ktime.h>
>
> #include <acpi/cppc_acpi.h>
> +#ifdef CONFIG_X86
> +#include <asm/msr.h>
> +#endif
Please figure out how to avoid this.
> +
> /*
> * Lock to provide mutually exclusive access to the PCC
> * channel. e.g. When the remote updates the shared region
> @@ -585,8 +589,9 @@ int acpi_cppc_processor_probe(struct acpi_processor *pr)
> pr_debug("Mismatched PCC ids.\n");
> goto out_free;
> }
> - } else if (gas_t->space_id != ACPI_ADR_SPACE_SYSTEM_MEMORY) {
> - /* Support only PCC and SYS MEM type regs */
> + } else if (gas_t->space_id != ACPI_ADR_SPACE_SYSTEM_MEMORY &&
> + gas_t->space_id != ACPI_ADR_SPACE_FIXED_HARDWARE) {
> + /* Support only PCC, FFH and SYS MEM type regs */
> pr_debug("Unsupported register type: %d\n", gas_t->space_id);
> goto out_free;
> }
> @@ -645,13 +650,59 @@ void acpi_cppc_processor_exit(struct acpi_processor *pr)
> }
> EXPORT_SYMBOL_GPL(acpi_cppc_processor_exit);
>
> +#ifdef CONFIG_X86
> +static int cpc_read_ffh(int cpunum, struct cpc_reg *reg, u64 *val)
> +{
> + int err;
> +
> + err = rdmsrl_on_cpu(cpunum, reg->address, val);
> + if (!err) {
> + u64 mask = GENMASK_ULL(reg->bit_offset + reg->bit_width - 1,
> + reg->bit_offset);
> +
> + *val &= mask;
> + *val >>= reg->bit_offset;
> + }
> + return err;
> +}
> +
> +static int cpc_write_ffh(int cpunum, struct cpc_reg *reg, u64 val)
> +{
> + u64 rd_val;
> + int err;
> +
> + err = rdmsrl_on_cpu(cpunum, reg->address, &rd_val);
> + if (!err) {
> + u64 mask = GENMASK_ULL(reg->bit_offset + reg->bit_width - 1,
> + reg->bit_offset);
> +
> + val <<= reg->bit_offset;
> + val &= mask;
> + rd_val &= ~mask;
> + rd_val |= val;
> + err = wrmsrl_on_cpu(cpunum, reg->address, rd_val);
> + }
> + return err;
> +}
The above really should go somewhere under arch/x86/.
> +#else
> +static int cpc_read_ffh(int cpunum, struct cpc_reg *reg, u64 *val)
> +{
> + return -EINVAL;
> +}
> +static int cpc_write_ffh(int cpunum, struct cpc_reg *reg, u64 val)
> +{
> + return -EINVAL;
> +
> +}
And I would defined these as __weak functions.
Also another return value like -ENOTSUPP for example would better IMO.
> +#endif
> +
> /*
> * Since cpc_read and cpc_write are called while holding pcc_lock, it should be
> * as fast as possible. We have already mapped the PCC subspace during init, so
> * we can directly write to it.
> */
>
> -static int cpc_read(struct cpc_register_resource *res, u64 *val)
> +static int cpc_read(int cpunum, struct cpc_register_resource *res, u64 *val)
> {
> struct cpc_reg *reg = &res->cpc_entry.reg;
> int ret_val = 0;
> @@ -684,13 +735,15 @@ static int cpc_read(struct cpc_register_resource *res, u64 *val)
> reg->bit_width);
> ret_val = -EFAULT;
> }
> + } else if (reg->space_id == ACPI_ADR_SPACE_FIXED_HARDWARE) {
> + ret_val = cpc_read_ffh(cpunum, reg, val);
> } else
> ret_val = acpi_os_read_memory((acpi_physical_address)reg->address,
> val, reg->bit_width);
> return ret_val;
> }
>
> -static int cpc_write(struct cpc_reg *reg, u64 val)
> +static int cpc_write(int cpunum, struct cpc_reg *reg, u64 val)
> {
> int ret_val = 0;
>
> @@ -716,6 +769,8 @@ static int cpc_write(struct cpc_reg *reg, u64 val)
> ret_val = -EFAULT;
> break;
> }
> + } else if (reg->space_id == ACPI_ADR_SPACE_FIXED_HARDWARE) {
> + ret_val = cpc_write_ffh(cpunum, reg, val);
> } else
> ret_val = acpi_os_write_memory((acpi_physical_address)reg->address,
> val, reg->bit_width);
> @@ -761,16 +816,16 @@ int cppc_get_perf_caps(int cpunum, struct cppc_perf_caps *perf_caps)
> }
> }
>
> - cpc_read(highest_reg, &high);
> + cpc_read(cpunum, highest_reg, &high);
> perf_caps->highest_perf = high;
>
> - cpc_read(lowest_reg, &low);
> + cpc_read(cpunum, lowest_reg, &low);
> perf_caps->lowest_perf = low;
>
> - cpc_read(ref_perf, &ref);
> + cpc_read(cpunum, ref_perf, &ref);
> perf_caps->reference_perf = ref;
>
> - cpc_read(nom_perf, &nom);
> + cpc_read(cpunum, nom_perf, &nom);
> perf_caps->nominal_perf = nom;
>
> if (!ref)
> @@ -819,8 +874,8 @@ int cppc_get_perf_ctrs(int cpunum, struct cppc_perf_fb_ctrs *perf_fb_ctrs)
> }
> }
>
> - cpc_read(delivered_reg, &delivered);
> - cpc_read(reference_reg, &reference);
> + cpc_read(cpunum, delivered_reg, &delivered);
> + cpc_read(cpunum, reference_reg, &reference);
>
> if (!delivered || !reference) {
> ret = -EFAULT;
> @@ -875,7 +930,7 @@ int cppc_set_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls)
> * Skip writing MIN/MAX until Linux knows how to come up with
> * useful values.
> */
> - cpc_write(&desired_reg->cpc_entry.reg, perf_ctrls->desired_perf);
> + cpc_write(cpu, &desired_reg->cpc_entry.reg, perf_ctrls->desired_perf);
>
> /* Is this a PCC reg ?*/
> if (desired_reg->cpc_entry.reg.space_id == ACPI_ADR_SPACE_PLATFORM_COMM) {
>
Thanks,
Rafael
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