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Date: Tue, 4 Jan 2022 21:02:32 +0100
From: "Rafael J. Wysocki" <rafael@...nel.org>
To: Sudeep Holla <sudeep.holla@....com>
Cc: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
"Rafael J . Wysocki" <rafael@...nel.org>,
kernel test robot <lkp@...el.com>
Subject: Re: [PATCH v3] ACPI: PCC: Implement OperationRegion handler for the
PCC Type 3 subtype
On Tue, Jan 4, 2022 at 8:51 PM Sudeep Holla <sudeep.holla@....com> wrote:
>
> PCC OpRegion provides a mechanism to communicate with the platform
> directly from the AML. PCCT provides the list of PCC channel available
> in the platform, a subset or all of them can be used in PCC Opregion.
>
> This patch registers the PCC OpRegion handler before ACPI tables are
> loaded. This relies on the special context data passed to identify and
> set up the PCC channel before the OpRegion handler is executed for the
> first time.
>
> Typical PCC Opregion declaration looks like this:
>
> OperationRegion (PFRM, PCC, 2, 0x74)
> Field (PFRM, ByteAcc, NoLock, Preserve)
> {
> SIGN, 32,
> FLGS, 32,
> LEN, 32,
> CMD, 32,
> DATA, 800
> }
>
> It contains four named double words followed by 100 bytes of buffer
> names DATA.
>
> ASL can fill out the buffer something like:
>
> /* Create global or local buffer */
> Name (BUFF, Buffer (0x0C){})
> /* Create double word fields over the buffer */
> CreateDWordField (BUFF, 0x0, WD0)
> CreateDWordField (BUFF, 0x04, WD1)
> CreateDWordField (BUFF, 0x08, WD2)
>
> /* Fill the named fields */
> WD0 = 0x50434300
> SIGN = BUFF
> WD0 = 1
> FLGS = BUFF
> WD0 = 0x10
> LEN = BUFF
>
> /* Fill the payload in the DATA buffer */
> WD0 = 0
> WD1 = 0x08
> WD2 = 0
> DATA = BUFF
>
> /* Write to CMD field to trigger handler */
> WD0 = 0x4404
> CMD = BUFF
>
> This buffer is received by acpi_pcc_opregion_space_handler. This
> handler will fetch the complete buffer via internal_pcc_buffer.
>
> The setup handler will receive the special PCC context data which will
> contain the PCC channel index which used to set up the channel. The
> buffer pointer and length is saved in region context which is then used
> in the handler.
>
> (kernel test robot: Build failure with CONFIG_ACPI_DEBUGGER)
> Link: https://lore.kernel.org/r/202201041539.feAV0l27-lkp@intel.com
> Reported-by: kernel test robot <lkp@...el.com>
> Cc: Rafael J. Wysocki <rafael@...nel.org>
> Signed-off-by: Sudeep Holla <sudeep.holla@....com>
Applied as 5.17 material, thanks!
> ---
> drivers/acpi/Kconfig | 17 ++++++
> drivers/acpi/Makefile | 1 +
> drivers/acpi/acpi_pcc.c | 120 ++++++++++++++++++++++++++++++++++++++++
> drivers/acpi/bus.c | 1 +
> include/linux/acpi.h | 6 ++
> 5 files changed, 145 insertions(+)
> create mode 100644 drivers/acpi/acpi_pcc.c
>
> v2[2]-v3:
> - Fixed build with CONFIG_ACPI_DEBUGGER enabled
> Looks like return_ACPI_STATUS is supposed to be used only
> in core ACPICA
>
> v1[0]-v2[2]:
> - Addressed all the comments from Rafael[1]
>
> [0] https://lore.kernel.org/r/20211222190919.137550-1-sudeep.holla@arm.com/
> [1] https://lore.kernel.org/r/CAJZ5v0jWJVSFS3KTavfCTzxWq-Q361nGDCWf+VLXRu-9Z4MJsQ@mail.gmail.com
> [2] https://lore.kernel.org/r/20220103155838.616580-1-sudeep.holla@arm.com
>
> diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
> index 91f1da16934d..8cdc7860b6e6 100644
> --- a/drivers/acpi/Kconfig
> +++ b/drivers/acpi/Kconfig
> @@ -546,6 +546,23 @@ config ACPI_PPTT
> bool
> endif
>
> +config ACPI_PCC
> + bool "ACPI PCC Address Space"
> + depends on PCC
> + default y
> + help
> + 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.
> +
> + Enable this feature if you want to set up and install the PCC Address
> + Space handler to handle PCC OpRegion in the firmware.
> +
> source "drivers/acpi/pmic/Kconfig"
>
> config ACPI_VIOT
> diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
> index d3dc79298ce3..f47032769f69 100644
> --- a/drivers/acpi/Makefile
> +++ b/drivers/acpi/Makefile
> @@ -67,6 +67,7 @@ acpi-$(CONFIG_ACPI_LPIT) += acpi_lpit.o
> acpi-$(CONFIG_ACPI_GENERIC_GSI) += irq.o
> acpi-$(CONFIG_ACPI_WATCHDOG) += acpi_watchdog.o
> acpi-$(CONFIG_ACPI_PRMT) += prmt.o
> +acpi-$(CONFIG_ACPI_PCC) += acpi_pcc.o
>
> # Address translation
> acpi-$(CONFIG_ACPI_ADXL) += acpi_adxl.o
> diff --git a/drivers/acpi/acpi_pcc.c b/drivers/acpi/acpi_pcc.c
> new file mode 100644
> index 000000000000..41e3ebd204ff
> --- /dev/null
> +++ b/drivers/acpi/acpi_pcc.c
> @@ -0,0 +1,120 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Author: Sudeep Holla <sudeep.holla@....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>
> +
> +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;
> +};
> +
> +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;
> +
> + 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);
> + return AE_NOT_FOUND;
> + }
> +
> + pcc_chan = data->pcc_chan;
> + 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);
> + return AE_NO_MEMORY;
> + }
> +
> + *region_context = data;
> + return AE_OK;
> +}
> +
> +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;
> +
> + 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;
> +
> + if (data->pcc_chan->mchan->mbox->txdone_irq)
> + wait_for_completion(&data->done);
> +
> + mbox_client_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");
> +}
> diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
> index dd535b4b9a16..75a61626eddd 100644
> --- a/drivers/acpi/bus.c
> +++ b/drivers/acpi/bus.c
> @@ -1320,6 +1320,7 @@ static int __init acpi_init(void)
> pr_debug("%s: kset create error\n", __func__);
>
> init_prmt();
> + acpi_init_pcc();
> result = acpi_bus_init();
> if (result) {
> kobject_put(acpi_kobj);
> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
> index 6c0798db6bde..eaeb4b9255bc 100644
> --- a/include/linux/acpi.h
> +++ b/include/linux/acpi.h
> @@ -1389,6 +1389,12 @@ static inline int find_acpi_cpu_cache_topology(unsigned int cpu, int level)
> }
> #endif
>
> +#ifdef CONFIG_ACPI_PCC
> +void acpi_init_pcc(void);
> +#else
> +static inline void acpi_init_pcc(void) { }
> +#endif
> +
> #ifdef CONFIG_ACPI
> extern void acpi_device_notify(struct device *dev);
> extern void acpi_device_notify_remove(struct device *dev);
>
> base-commit: 7a716cec17d19211715a34b426aafc3fadb22de6
> --
> 2.25.1
>
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