Re: [Intel-gfx] [PATCH v10 2/5] mei: add support for graphics system controller (gsc) devices

["Ceraolo Spurio, Daniele" <daniele.ceraolospurio@intel.com>]

On 3/8/2022 8:36 AM, Alexander Usyskin wrote:
> From: Tomas Winkler <tomas.winkler@intel.com>
>
> GSC is a graphics system controller, based on CSE, it provides
> a chassis controller for graphics discrete cards, as well as it
> supports media protection on selected devices.
>
> mei_gsc binds to a auxiliary devices exposed by Intel discrete
> driver i915.
>
> Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com>
> Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
> ---
>   drivers/misc/mei/Kconfig  |  14 +++
>   drivers/misc/mei/Makefile |   3 +
>   drivers/misc/mei/gsc-me.c | 186 ++++++++++++++++++++++++++++++++++++++
>   drivers/misc/mei/hw-me.c  |  27 +++++-
>   drivers/misc/mei/hw-me.h  |   2 +
>   5 files changed, 230 insertions(+), 2 deletions(-)
>   create mode 100644 drivers/misc/mei/gsc-me.c
>
> diff --git a/drivers/misc/mei/Kconfig b/drivers/misc/mei/Kconfig
> index 0e0bcd0da852..d21486d69df2 100644
> --- a/drivers/misc/mei/Kconfig
> +++ b/drivers/misc/mei/Kconfig
> @@ -46,6 +46,20 @@ config INTEL_MEI_TXE
>   	  Supported SoCs:
>   	  Intel Bay Trail
>   
> +config INTEL_MEI_GSC

On platforms with a GSC, INTEL_MEI_PXP depends on INTEL_MEI_GSC. Are you 
planning to add that dependency once the HECI1/PXP interface is exposed, 
or are you expecting i915 to check for both?

> +	tristate "Intel MEI GSC embedded device"
> +	depends on INTEL_MEI
> +	depends on INTEL_MEI_ME
> +	depends on X86 && PCI
> +	depends on DRM_I915
> +	help
> +	  Intel auxiliary driver for GSC devices embedded in Intel graphics devices.
> +
> +	  An MEI device here called GSC can be embedded in an
> +	  Intel graphics devices, to support a range of chassis
> +	  tasks such as graphics card firmware update and security
> +	  tasks.
> +
>   source "drivers/misc/mei/hdcp/Kconfig"
>   source "drivers/misc/mei/pxp/Kconfig"
>   
> diff --git a/drivers/misc/mei/Makefile b/drivers/misc/mei/Makefile
> index d8e5165917f2..fb740d754900 100644
> --- a/drivers/misc/mei/Makefile
> +++ b/drivers/misc/mei/Makefile
> @@ -18,6 +18,9 @@ obj-$(CONFIG_INTEL_MEI_ME) += mei-me.o
>   mei-me-objs := pci-me.o
>   mei-me-objs += hw-me.o
>   
> +obj-$(CONFIG_INTEL_MEI_GSC) += mei-gsc.o
> +mei-gsc-objs := gsc-me.o
> +
>   obj-$(CONFIG_INTEL_MEI_TXE) += mei-txe.o
>   mei-txe-objs := pci-txe.o
>   mei-txe-objs += hw-txe.o
> diff --git a/drivers/misc/mei/gsc-me.c b/drivers/misc/mei/gsc-me.c
> new file mode 100644
> index 000000000000..0afae70e0609
> --- /dev/null
> +++ b/drivers/misc/mei/gsc-me.c
> @@ -0,0 +1,186 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright(c) 2019-2022, Intel Corporation. All rights reserved.
> + *
> + * Intel Management Engine Interface (Intel MEI) Linux driver
> + */
> +
> +#include <linux/module.h>
> +#include <linux/mei_aux.h>
> +#include <linux/device.h>
> +#include <linux/irqreturn.h>
> +#include <linux/jiffies.h>
> +#include <linux/ktime.h>
> +#include <linux/delay.h>
> +#include <linux/pm_runtime.h>
> +
> +#include "mei_dev.h"
> +#include "hw-me.h"
> +#include "hw-me-regs.h"
> +
> +#include "mei-trace.h"
> +
> +#define MEI_GSC_RPM_TIMEOUT 500

MEI_ME_RPM_TIMEOUT already exists in hw-me.h with the same value. If 
you're not expecting them to diverge, we could just re-use the existing 
one. Not a blocker.

> +
> +static int mei_gsc_read_hfs(const struct mei_device *dev, int where, u32 *val)
> +{
> +	struct mei_me_hw *hw = to_me_hw(dev);
> +
> +	*val = ioread32(hw->mem_addr + where + 0xC00);
> +
> +	return 0;
> +}
> +
> +static int mei_gsc_probe(struct auxiliary_device *aux_dev,
> +			 const struct auxiliary_device_id *aux_dev_id)
> +{
> +	struct mei_aux_device *adev = auxiliary_dev_to_mei_aux_dev(aux_dev);
> +	struct mei_device *dev;

might be worth renaming this variable to mei_dev, to avoid confusion 
with "device" below. Not a blocker.

> +	struct mei_me_hw *hw;
> +	struct device *device;
> +	const struct mei_cfg *cfg;
> +	int ret;
> +
> +	cfg = mei_me_get_cfg(aux_dev_id->driver_data);
> +	if (!cfg)
> +		return -ENODEV;
> +
> +	device = &aux_dev->dev;
> +
> +	dev = mei_me_dev_init(device, cfg);
> +	if (IS_ERR(dev)) {
> +		ret = PTR_ERR(dev);
> +		goto err;
> +	}
> +
> +	hw = to_me_hw(dev);
> +	hw->mem_addr = devm_ioremap_resource(device, &adev->bar);
> +	if (IS_ERR(hw->mem_addr)) {
> +		dev_err(device, "mmio not mapped\n");
> +		ret = PTR_ERR(hw->mem_addr);
> +		goto err;
> +	}
> +
> +	hw->irq = adev->irq;
> +	hw->read_fws = mei_gsc_read_hfs;
> +
> +	dev_set_drvdata(&aux_dev->dev, dev);

you have a device = &aux_dev->dev earlier, so you can just use device here.

> +
> +	ret = devm_request_threaded_irq(device, hw->irq,
> +					mei_me_irq_quick_handler,
> +					mei_me_irq_thread_handler,
> +					IRQF_ONESHOT, KBUILD_MODNAME, dev);

If I'm understanding this correctly, you're tying the irq to the device 
allocated by i915, so if the probe fails below or the mei_gsc module is 
unloaded the irq is going to stick around. Probably better to clean it 
up explicitly, in case we get a spurious interrupt from the HW and i915 
propagates it (although that's a very unlikely scenario).

> +	if (ret) {
> +		dev_err(device, "irq register failed %d\n", ret);
> +		goto err;
> +	}
> +
> +	pm_runtime_get_noresume(device);
> +	pm_runtime_set_active(device);
> +	pm_runtime_enable(device);
> +
> +	if (mei_start(dev)) {
> +		dev_err(device, "init hw failure.\n");
> +		ret = -ENODEV;
> +		goto err;
> +	}
> +
> +	pm_runtime_set_autosuspend_delay(device, MEI_GSC_RPM_TIMEOUT);
> +	pm_runtime_use_autosuspend(device);
> +
> +	ret = mei_register(dev, device);
> +	if (ret)
> +		goto register_err;
> +
> +	pm_runtime_put_noidle(device);
> +	return 0;
> +
> +register_err:
> +	mei_stop(dev);
> +
> +err:
> +	dev_err(device, "probe failed: %d\n", ret);
> +	dev_set_drvdata(&aux_dev->dev, NULL);

can use device here as well instead of &aux_dev->dev

> +	return ret;
> +}
> +
> +static void mei_gsc_remove(struct auxiliary_device *aux_dev)
> +{
> +	struct mei_device *dev;
> +
> +	dev = dev_get_drvdata(&aux_dev->dev);
> +	if (!dev)
> +		return;
> +
> +	mei_stop(dev);
> +
> +	mei_deregister(dev);
> +
> +	pm_runtime_disable(&aux_dev->dev);
> +}
> +
> +static int __maybe_unused mei_gsc_pm_suspend(struct device *device)
> +{
> +	struct mei_device *dev = dev_get_drvdata(device);
> +
> +	if (!dev)
> +		return -ENODEV;
> +
> +	mei_stop(dev);
> +
> +	mei_disable_interrupts(dev);
> +
> +	return 0;
> +}
> +
> +static int __maybe_unused mei_gsc_pm_resume(struct device *device)
> +{
> +	struct mei_device *dev = dev_get_drvdata(device);
> +	int err;
> +
> +	if (!dev)
> +		return -ENODEV;
> +
> +	err = mei_restart(dev);

Might be worth adding a comment to explain that the interrupts are 
enabled by the mei_restart and that's why we don't have a 
mei_interrupts_enable call to match the disable we have in the suspend.

Daniele

> +	if (err)
> +		return err;
> +
> +	/* Start timer if stopped in suspend */
> +	schedule_delayed_work(&dev->timer_work, HZ);
> +
> +	return 0;
> +}
> +
> +static SIMPLE_DEV_PM_OPS(mei_gsc_pm_ops, mei_gsc_pm_suspend, mei_gsc_pm_resume);
> +
> +static const struct auxiliary_device_id mei_gsc_id_table[] = {
> +	{
> +		.name = "i915.mei-gsc",
> +		.driver_data = MEI_ME_GSC_CFG,
> +
> +	},
> +	{
> +		.name = "i915.mei-gscfi",
> +		.driver_data = MEI_ME_GSCFI_CFG,
> +	},
> +	{
> +		/* sentinel */
> +	}
> +};
> +MODULE_DEVICE_TABLE(auxiliary, mei_gsc_id_table);
> +
> +static struct auxiliary_driver mei_gsc_driver = {
> +	.probe	= mei_gsc_probe,
> +	.remove = mei_gsc_remove,
> +	.driver = {
> +		/* auxiliary_driver_register() sets .name to be the modname */
> +		.pm = &mei_gsc_pm_ops,
> +	},
> +	.id_table = mei_gsc_id_table
> +};
> +module_auxiliary_driver(mei_gsc_driver);
> +
> +MODULE_AUTHOR("Intel Corporation");
> +MODULE_ALIAS("auxiliary:i915.mei-gsc");
> +MODULE_ALIAS("auxiliary:i915.mei-gscfi");
> +MODULE_LICENSE("GPL v2");
> diff --git a/drivers/misc/mei/hw-me.c b/drivers/misc/mei/hw-me.c
> index d3a6c0728645..9748d14849a1 100644
> --- a/drivers/misc/mei/hw-me.c
> +++ b/drivers/misc/mei/hw-me.c
> @@ -1226,6 +1226,7 @@ irqreturn_t mei_me_irq_quick_handler(int irq, void *dev_id)
>   	me_intr_disable(dev, hcsr);
>   	return IRQ_WAKE_THREAD;
>   }
> +EXPORT_SYMBOL_GPL(mei_me_irq_quick_handler);
>   
>   /**
>    * mei_me_irq_thread_handler - function called after ISR to handle the interrupt
> @@ -1320,6 +1321,7 @@ irqreturn_t mei_me_irq_thread_handler(int irq, void *dev_id)
>   	mutex_unlock(&dev->device_lock);
>   	return IRQ_HANDLED;
>   }
> +EXPORT_SYMBOL_GPL(mei_me_irq_thread_handler);
>   
>   static const struct mei_hw_ops mei_me_hw_ops = {
>   
> @@ -1433,6 +1435,12 @@ static bool mei_me_fw_type_sps(const struct pci_dev *pdev)
>   #define MEI_CFG_KIND_ITOUCH                     \
>   	.kind = "itouch"
>   
> +#define MEI_CFG_TYPE_GSC                        \
> +	.kind = "gsc"
> +
> +#define MEI_CFG_TYPE_GSCFI                      \
> +	.kind = "gscfi"
> +
>   #define MEI_CFG_FW_SPS                          \
>   	.quirk_probe = mei_me_fw_type_sps
>   
> @@ -1565,6 +1573,18 @@ static const struct mei_cfg mei_me_pch15_sps_cfg = {
>   	MEI_CFG_FW_SPS,
>   };
>   
> +/* Graphics System Controller */
> +static const struct mei_cfg mei_me_gsc_cfg = {
> +	MEI_CFG_TYPE_GSC,
> +	MEI_CFG_PCH8_HFS,
> +};
> +
> +/* Graphics System Controller Firmware Interface */
> +static const struct mei_cfg mei_me_gscfi_cfg = {
> +	MEI_CFG_TYPE_GSCFI,
> +	MEI_CFG_PCH8_HFS,
> +};
> +
>   /*
>    * mei_cfg_list - A list of platform platform specific configurations.
>    * Note: has to be synchronized with  enum mei_cfg_idx.
> @@ -1585,6 +1605,8 @@ static const struct mei_cfg *const mei_cfg_list[] = {
>   	[MEI_ME_PCH12_SPS_ITOUCH_CFG] = &mei_me_pch12_itouch_sps_cfg,
>   	[MEI_ME_PCH15_CFG] = &mei_me_pch15_cfg,
>   	[MEI_ME_PCH15_SPS_CFG] = &mei_me_pch15_sps_cfg,
> +	[MEI_ME_GSC_CFG] = &mei_me_gsc_cfg,
> +	[MEI_ME_GSCFI_CFG] = &mei_me_gscfi_cfg,
>   };
>   
>   const struct mei_cfg *mei_me_get_cfg(kernel_ulong_t idx)
> @@ -1595,7 +1617,8 @@ const struct mei_cfg *mei_me_get_cfg(kernel_ulong_t idx)
>   		return NULL;
>   
>   	return mei_cfg_list[idx];
> -};
> +}
> +EXPORT_SYMBOL_GPL(mei_me_get_cfg);
>   
>   /**
>    * mei_me_dev_init - allocates and initializes the mei device structure
> @@ -1630,4 +1653,4 @@ struct mei_device *mei_me_dev_init(struct device *parent,
>   
>   	return dev;
>   }
> -
> +EXPORT_SYMBOL_GPL(mei_me_dev_init);
> diff --git a/drivers/misc/mei/hw-me.h b/drivers/misc/mei/hw-me.h
> index 00a7132ac7a2..a071c645e905 100644
> --- a/drivers/misc/mei/hw-me.h
> +++ b/drivers/misc/mei/hw-me.h
> @@ -112,6 +112,8 @@ enum mei_cfg_idx {
>   	MEI_ME_PCH12_SPS_ITOUCH_CFG,
>   	MEI_ME_PCH15_CFG,
>   	MEI_ME_PCH15_SPS_CFG,
> +	MEI_ME_GSC_CFG,
> +	MEI_ME_GSCFI_CFG,
>   	MEI_ME_NUM_CFG,
>   };
>