Re: [v7 08/10] platform/x86/amd/hsmp: Create mutually exclusive ACPI and plat drivers

[Suma Hegde <Suma.Hegde@amd.com>]

Hi Hans,

On 9/5/2024 12:22 AM, Hans de Goede wrote:
> Caution: This message originated from an External Source. Use proper caution when opening attachments, clicking links, or responding.
>
>
> Hi,
>
> On 9/3/24 2:38 PM, Suma Hegde wrote:
>> Separate the probes for HSMP ACPI and platform device drivers.
>>
>> Provide a Kconfig option to choose between
>> ACPI or the platform device based driver.
>> The common code which is the core part of the HSMP driver
>> maintained at hsmp.c is guarded by AMD_HSMP config and is selected by
>> these two driver configs.
> <snip>
>
>> diff --git a/drivers/platform/x86/amd/hsmp/Kconfig b/drivers/platform/x86/amd/hsmp/Kconfig
>> index b55d4ed9bceb..b10ff91e9f5a 100644
>> --- a/drivers/platform/x86/amd/hsmp/Kconfig
>> +++ b/drivers/platform/x86/amd/hsmp/Kconfig
>> @@ -4,14 +4,45 @@
>>   #
>>
>>   config AMD_HSMP
>> -     tristate "AMD HSMP Driver"
>> -     depends on AMD_NB && X86_64 && ACPI
>> +     tristate
>> +
>> +menu "AMD HSMP Driver"
>> +     depends on AMD_NB || COMPILE_TEST
>> +
>> +config AMD_HSMP_ACPI
>> +     tristate "AMD HSMP ACPI device driver"
>> +     depends on ACPI
>> +     select AMD_HSMP
>>        help
>> +       Host System Management Port (HSMP) interface is a mailbox interface
>> +       between the x86 core and the System Management Unit (SMU) firmware.
>>          The driver provides a way for user space tools to monitor and manage
>> -       system management functionality on EPYC server CPUs from AMD.
>> +       system management functionality on EPYC and MI300A server CPUs
>> +       from AMD.
>> +
>> +       This option supports ACPI based probing.
>> +       You may enable this, if your platform BIOS provides an ACPI object
>> +       as described in amd_hsmp.rst document.
>> +
>> +       If you choose to compile this driver as a module the module will be
>> +       called amd_hsmp.
>>
>> +config AMD_HSMP_PLAT
>> +     tristate "AMD HSMP platform device driver"
>> +     depends on AMD_HSMP_ACPI=n
> I was about to merge this series, but this is going to cause
> a regression for users running distro kernels which rely on
> the old legacy probing.
>
> So before this we had 1 driver which would auto-load on systems
> which have the new ACPI description of the HSMP and which could
> be manually modprobed on systems which require the legacy enumeration.
>
> But now if linux distributions enable AMD_HSMP_ACPI then there
> will be no way for users with systems which lack the ACPI description
> of the HSMP to still get HSMP support.
>
> I guess what you want here is to avoid the legacy driver loading
> on systems which do have the ACPI description. But the way to do
> that would be to do a runtime check for the ACPI description,
> not disallow building the legacy driver altogether.
>
> E.g. you could do the following in hsmp_plt_init() :
>
>          if (acpi_dev_present(ACPI_HSMP_DEVICE_HID, NULL, -1)) {
>                  pr_err("The legacy HSMP driver cannot load on this system, please use hsmp_acpi instead\n");
>                  return -ENODEV;
>          }
>
> I see that you also build both drivers into a single module,
> yes then you cannot have both because you cannot have 2 init
> functions.
>
> Please split things into 3 modules, one shared hsmp_common.ko +
> a hsmp_acpi.ko + hsmp_legacy.ko

Ok, I will keep Kconfig as is with 3 config symbols, but will remove 
"depends on AMD_HSMP_ACPI=n" and modify the Makefile to build 3 modules.

hsmp_common.ko, + amd_hsmp.ko (instead of hsmp_legacy.ko, keeping name 
as amd_hsmp.ko to keep legacy name for the legacy module).

+ hsmp_acpi.ko.

Also will add a check acpi_dev_present() as mentioned above in 
hsmp_plt_init().

Because of the change in config symbols, Linux distributions have to 
enable either AMD_HSMP_ACPI or AMD_HSMP_PLAT or both to get HSMP modules 
compiled.

> Regards,
>
> Hans

Thanks and Regards,

Suma

>
>
>
>
>> +     select AMD_HSMP
>> +     help
>>          Host System Management Port (HSMP) interface is a mailbox interface
>>          between the x86 core and the System Management Unit (SMU) firmware.
>> +       The driver provides a way for user space tools to monitor and manage
>> +       system management functionality on EPYC and MI300A server CPUs
>> +       from AMD.
>> +
>> +       This option supports platform device based probing.
>> +       You may enable this, if your platform BIOS does not provide
>> +       HSMP ACPI object.
>>
>>          If you choose to compile this driver as a module the module will be
>>          called amd_hsmp.
>> +
>> +endmenu
>> diff --git a/drivers/platform/x86/amd/hsmp/Makefile b/drivers/platform/x86/amd/hsmp/Makefile
>> index 0cc92865c0a2..18d9a0d1e8c5 100644
>> --- a/drivers/platform/x86/amd/hsmp/Makefile
>> +++ b/drivers/platform/x86/amd/hsmp/Makefile
>> @@ -4,5 +4,7 @@
>>   # AMD HSMP Driver
>>   #
>>
>> -obj-$(CONFIG_AMD_HSMP)               += amd_hsmp.o
>> -amd_hsmp-objs                        := hsmp.o plat.o acpi.o
>> +obj-$(CONFIG_AMD_HSMP)                       += amd_hsmp.o
>> +amd_hsmp-objs                                := hsmp.o
>> +amd_hsmp-$(CONFIG_AMD_HSMP_PLAT)     += plat.o
>> +amd_hsmp-$(CONFIG_AMD_HSMP_ACPI)     += acpi.o
>> diff --git a/drivers/platform/x86/amd/hsmp/acpi.c b/drivers/platform/x86/amd/hsmp/acpi.c
>> index 6f8e7962266a..766617e6adc7 100644
>> --- a/drivers/platform/x86/amd/hsmp/acpi.c
>> +++ b/drivers/platform/x86/amd/hsmp/acpi.c
>> @@ -9,11 +9,15 @@
>>
>>   #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
>>
>> +#include <asm/amd_nb.h>
>> +
>>   #include <linux/acpi.h>
>>   #include <linux/device.h>
>>   #include <linux/dev_printk.h>
>>   #include <linux/ioport.h>
>>   #include <linux/kstrtox.h>
>> +#include <linux/module.h>
>> +#include <linux/platform_device.h>
>>   #include <linux/sysfs.h>
>>   #include <linux/uuid.h>
>>
>> @@ -21,6 +25,10 @@
>>
>>   #include "hsmp.h"
>>
>> +#define DRIVER_NAME          "amd_hsmp"
>> +#define DRIVER_VERSION               "2.3"
>> +#define ACPI_HSMP_DEVICE_HID "AMDI0097"
>> +
>>   /* These are the strings specified in ACPI table */
>>   #define MSG_IDOFF_STR                "MsgIdOffset"
>>   #define MSG_ARGOFF_STR               "MsgArgOffset"
>> @@ -200,7 +208,6 @@ static int hsmp_parse_acpi_table(struct device *dev, u16 sock_ind)
>>        sock->sock_ind          = sock_ind;
>>        sock->dev               = dev;
>>        sock->amd_hsmp_rdwr     = amd_hsmp_acpi_rdwr;
>> -     hsmp_pdev.is_acpi_device        = true;
>>
>>        sema_init(&sock->hsmp_sem, 1);
>>
>> @@ -213,7 +220,7 @@ static int hsmp_parse_acpi_table(struct device *dev, u16 sock_ind)
>>        return hsmp_read_acpi_dsd(sock);
>>   }
>>
>> -int hsmp_create_acpi_sysfs_if(struct device *dev)
>> +static int hsmp_create_acpi_sysfs_if(struct device *dev)
>>   {
>>        struct attribute_group *attr_grp;
>>        u16 sock_ind;
>> @@ -236,7 +243,7 @@ int hsmp_create_acpi_sysfs_if(struct device *dev)
>>        return devm_device_add_group(dev, attr_grp);
>>   }
>>
>> -int init_acpi(struct device *dev)
>> +static int init_acpi(struct device *dev)
>>   {
>>        u16 sock_ind;
>>        int ret;
>> @@ -270,3 +277,72 @@ int init_acpi(struct device *dev)
>>
>>        return ret;
>>   }
>> +
>> +static const struct acpi_device_id amd_hsmp_acpi_ids[] = {
>> +     {ACPI_HSMP_DEVICE_HID, 0},
>> +     {}
>> +};
>> +MODULE_DEVICE_TABLE(acpi, amd_hsmp_acpi_ids);
>> +
>> +static int hsmp_acpi_probe(struct platform_device *pdev)
>> +{
>> +     int ret;
>> +
>> +     if (!hsmp_pdev.is_probed) {
>> +             hsmp_pdev.num_sockets = amd_nb_num();
>> +             if (hsmp_pdev.num_sockets == 0 || hsmp_pdev.num_sockets > MAX_AMD_SOCKETS)
>> +                     return -ENODEV;
>> +
>> +             hsmp_pdev.sock = devm_kcalloc(&pdev->dev, hsmp_pdev.num_sockets,
>> +                                           sizeof(*hsmp_pdev.sock),
>> +                                           GFP_KERNEL);
>> +             if (!hsmp_pdev.sock)
>> +                     return -ENOMEM;
>> +     }
>> +
>> +     ret = init_acpi(&pdev->dev);
>> +     if (ret) {
>> +             dev_err(&pdev->dev, "Failed to initialize HSMP interface.\n");
>> +             return ret;
>> +     }
>> +
>> +     ret = hsmp_create_acpi_sysfs_if(&pdev->dev);
>> +     if (ret)
>> +             dev_err(&pdev->dev, "Failed to create HSMP sysfs interface\n");
>> +
>> +     if (!hsmp_pdev.is_probed) {
>> +             ret = hsmp_misc_register(&pdev->dev);
>> +             if (ret)
>> +                     return ret;
>> +             hsmp_pdev.is_probed = true;
>> +     }
>> +
>> +     return 0;
>> +}
>> +
>> +static void hsmp_acpi_remove(struct platform_device *pdev)
>> +{
>> +     /*
>> +      * We register only one misc_device even on multi-socket system.
>> +      * So, deregister should happen only once.
>> +      */
>> +     if (hsmp_pdev.is_probed) {
>> +             hsmp_misc_deregister();
>> +             hsmp_pdev.is_probed = false;
>> +     }
>> +}
>> +
>> +static struct platform_driver amd_hsmp_driver = {
>> +     .probe          = hsmp_acpi_probe,
>> +     .remove_new     = hsmp_acpi_remove,
>> +     .driver         = {
>> +             .name   = DRIVER_NAME,
>> +             .acpi_match_table = amd_hsmp_acpi_ids,
>> +     },
>> +};
>> +
>> +module_platform_driver(amd_hsmp_driver);
>> +
>> +MODULE_DESCRIPTION("AMD HSMP Platform Interface Driver");
>> +MODULE_VERSION(DRIVER_VERSION);
>> +MODULE_LICENSE("GPL");
>> diff --git a/drivers/platform/x86/amd/hsmp/hsmp.c b/drivers/platform/x86/amd/hsmp/hsmp.c
>> index 78945750d590..5e0c9c36f435 100644
>> --- a/drivers/platform/x86/amd/hsmp/hsmp.c
>> +++ b/drivers/platform/x86/amd/hsmp/hsmp.c
>> @@ -15,17 +15,11 @@
>>   #include <linux/acpi.h>
>>   #include <linux/delay.h>
>>   #include <linux/device.h>
>> -#include <linux/module.h>
>> -#include <linux/platform_device.h>
>>   #include <linux/semaphore.h>
>>   #include <linux/sysfs.h>
>>
>>   #include "hsmp.h"
>>
>> -#define DRIVER_NAME          "amd_hsmp"
>> -#define DRIVER_VERSION               "2.2"
>> -#define ACPI_HSMP_DEVICE_HID "AMDI0097"
>> -
>>   /* HSMP Status / Error codes */
>>   #define HSMP_STATUS_NOT_READY        0x00
>>   #define HSMP_STATUS_OK               0x01
>> @@ -228,7 +222,7 @@ int hsmp_test(u16 sock_ind, u32 value)
>>        return ret;
>>   }
>>
>> -static long hsmp_ioctl(struct file *fp, unsigned int cmd, unsigned long arg)
>> +long hsmp_ioctl(struct file *fp, unsigned int cmd, unsigned long arg)
>>   {
>>        int __user *arguser = (int  __user *)arg;
>>        struct hsmp_message msg = { 0 };
>> @@ -284,12 +278,6 @@ static long hsmp_ioctl(struct file *fp, unsigned int cmd, unsigned long arg)
>>        return 0;
>>   }
>>
>> -static const struct file_operations hsmp_fops = {
>> -     .owner          = THIS_MODULE,
>> -     .unlocked_ioctl = hsmp_ioctl,
>> -     .compat_ioctl   = hsmp_ioctl,
>> -};
>> -
>>   ssize_t hsmp_metric_tbl_read(struct file *filp, struct kobject *kobj,
>>                             struct bin_attribute *bin_attr, char *buf,
>>                             loff_t off, size_t count)
>> @@ -414,193 +402,25 @@ int hsmp_cache_proto_ver(u16 sock_ind)
>>        return ret;
>>   }
>>
>> -static const struct acpi_device_id amd_hsmp_acpi_ids[] = {
>> -     {ACPI_HSMP_DEVICE_HID, 0},
>> -     {}
>> -};
>> -MODULE_DEVICE_TABLE(acpi, amd_hsmp_acpi_ids);
>> -
>> -static bool check_acpi_support(struct device *dev)
>> -{
>> -     struct acpi_device *adev = ACPI_COMPANION(dev);
>> -
>> -     if (adev && !acpi_match_device_ids(adev, amd_hsmp_acpi_ids))
>> -             return true;
>> -
>> -     return false;
>> -}
>> -
>> -static int hsmp_pltdrv_probe(struct platform_device *pdev)
>> -{
>> -     int ret;
>> -
>> -     /*
>> -      * On ACPI supported BIOS, there is an ACPI HSMP device added for
>> -      * each socket, so the per socket probing, but the memory allocated for
>> -      * sockets should be contiguous to access it as an array,
>> -      * Hence allocate memory for all the sockets at once instead of allocating
>> -      * on each probe.
>> -      */
>> -     if (!hsmp_pdev.is_probed) {
>> -             hsmp_pdev.sock = devm_kcalloc(&pdev->dev, hsmp_pdev.num_sockets,
>> -                                           sizeof(*hsmp_pdev.sock),
>> -                                           GFP_KERNEL);
>> -             if (!hsmp_pdev.sock)
>> -                     return -ENOMEM;
>> -     }
>> -     if (check_acpi_support(&pdev->dev)) {
>> -             ret = init_acpi(&pdev->dev);
>> -             if (ret) {
>> -                     dev_err(&pdev->dev, "Failed to init HSMP mailbox\n");
>> -                     return ret;
>> -             }
>> -             ret = hsmp_create_acpi_sysfs_if(&pdev->dev);
>> -             if (ret)
>> -                     dev_err(&pdev->dev, "Failed to create HSMP sysfs interface\n");
>> -     } else {
>> -             ret = init_platform_device(&pdev->dev);
>> -             if (ret) {
>> -                     dev_err(&pdev->dev, "Failed to init HSMP mailbox\n");
>> -                     return ret;
>> -             }
>> -             ret = hsmp_create_non_acpi_sysfs_if(&pdev->dev);
>> -             if (ret)
>> -                     dev_err(&pdev->dev, "Failed to create HSMP sysfs interface\n");
>> -     }
>> -
>> -     if (!hsmp_pdev.is_probed) {
>> -             hsmp_pdev.mdev.name     = HSMP_CDEV_NAME;
>> -             hsmp_pdev.mdev.minor    = MISC_DYNAMIC_MINOR;
>> -             hsmp_pdev.mdev.fops     = &hsmp_fops;
>> -             hsmp_pdev.mdev.parent   = &pdev->dev;
>> -             hsmp_pdev.mdev.nodename = HSMP_DEVNODE_NAME;
>> -             hsmp_pdev.mdev.mode     = 0644;
>> -
>> -             ret = misc_register(&hsmp_pdev.mdev);
>> -             if (ret)
>> -                     return ret;
>> -
>> -             hsmp_pdev.is_probed = true;
>> -     }
>> -
>> -     return 0;
>> -
>> -}
>> -
>> -static void hsmp_pltdrv_remove(struct platform_device *pdev)
>> -{
>> -     /*
>> -      * We register only one misc_device even on multi socket system.
>> -      * So, deregister should happen only once.
>> -      */
>> -     if (hsmp_pdev.is_probed) {
>> -             misc_deregister(&hsmp_pdev.mdev);
>> -             hsmp_pdev.is_probed = false;
>> -     }
>> -}
>> -
>> -static struct platform_driver amd_hsmp_driver = {
>> -     .probe          = hsmp_pltdrv_probe,
>> -     .remove_new     = hsmp_pltdrv_remove,
>> -     .driver         = {
>> -             .name   = DRIVER_NAME,
>> -             .acpi_match_table = amd_hsmp_acpi_ids,
>> -     },
>> +static const struct file_operations hsmp_fops = {
>> +     .owner          = THIS_MODULE,
>> +     .unlocked_ioctl = hsmp_ioctl,
>> +     .compat_ioctl   = hsmp_ioctl,
>>   };
>>
>> -static struct platform_device *amd_hsmp_platdev;
>> -
>> -static int hsmp_plat_dev_register(void)
>> +int hsmp_misc_register(struct device *dev)
>>   {
>> -     int ret;
>> -
>> -     amd_hsmp_platdev = platform_device_alloc(DRIVER_NAME, PLATFORM_DEVID_NONE);
>> -     if (!amd_hsmp_platdev)
>> -             return -ENOMEM;
>> -
>> -     ret = platform_device_add(amd_hsmp_platdev);
>> -     if (ret)
>> -             platform_device_put(amd_hsmp_platdev);
>> -
>> -     return ret;
>> +     hsmp_pdev.mdev.name     = HSMP_CDEV_NAME;
>> +     hsmp_pdev.mdev.minor    = MISC_DYNAMIC_MINOR;
>> +     hsmp_pdev.mdev.fops     = &hsmp_fops;
>> +     hsmp_pdev.mdev.parent   = dev;
>> +     hsmp_pdev.mdev.nodename = HSMP_DEVNODE_NAME;
>> +     hsmp_pdev.mdev.mode     = 0644;
>> +
>> +     return misc_register(&hsmp_pdev.mdev);
>>   }
>>
>> -/*
>> - * This check is only needed for backward compatibility of previous platforms.
>> - * All new platforms are expected to support ACPI based probing.
>> - */
>> -static bool legacy_hsmp_support(void)
>> +void hsmp_misc_deregister(void)
>>   {
>> -     if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD)
>> -             return false;
>> -
>> -     switch (boot_cpu_data.x86) {
>> -     case 0x19:
>> -             switch (boot_cpu_data.x86_model) {
>> -             case 0x00 ... 0x1F:
>> -             case 0x30 ... 0x3F:
>> -             case 0x90 ... 0x9F:
>> -             case 0xA0 ... 0xAF:
>> -                     return true;
>> -             default:
>> -                     return false;
>> -             }
>> -     case 0x1A:
>> -             switch (boot_cpu_data.x86_model) {
>> -             case 0x00 ... 0x1F:
>> -                     return true;
>> -             default:
>> -                     return false;
>> -             }
>> -     default:
>> -             return false;
>> -     }
>> -
>> -     return false;
>> +     misc_deregister(&hsmp_pdev.mdev);
>>   }
>> -
>> -static int __init hsmp_plt_init(void)
>> -{
>> -     int ret = -ENODEV;
>> -
>> -     /*
>> -      * amd_nb_num() returns number of SMN/DF interfaces present in the system
>> -      * if we have N SMN/DF interfaces that ideally means N sockets
>> -      */
>> -     hsmp_pdev.num_sockets = amd_nb_num();
>> -     if (hsmp_pdev.num_sockets == 0 || hsmp_pdev.num_sockets > MAX_AMD_SOCKETS)
>> -             return ret;
>> -
>> -     ret = platform_driver_register(&amd_hsmp_driver);
>> -     if (ret)
>> -             return ret;
>> -
>> -     if (!hsmp_pdev.is_acpi_device) {
>> -             if (legacy_hsmp_support()) {
>> -                     /* Not ACPI device, but supports HSMP, register a plat_dev */
>> -                     ret = hsmp_plat_dev_register();
>> -             } else {
>> -                     /* Not ACPI, Does not support HSMP */
>> -                     pr_info("HSMP is not supported on Family:%x model:%x\n",
>> -                             boot_cpu_data.x86, boot_cpu_data.x86_model);
>> -                     ret = -ENODEV;
>> -             }
>> -             if (ret)
>> -                     platform_driver_unregister(&amd_hsmp_driver);
>> -     }
>> -
>> -     return ret;
>> -}
>> -
>> -static void __exit hsmp_plt_exit(void)
>> -{
>> -     platform_device_unregister(amd_hsmp_platdev);
>> -     platform_driver_unregister(&amd_hsmp_driver);
>> -}
>> -
>> -device_initcall(hsmp_plt_init);
>> -module_exit(hsmp_plt_exit);
>> -
>> -MODULE_DESCRIPTION("AMD HSMP Platform Interface Driver");
>> -MODULE_VERSION(DRIVER_VERSION);
>> -MODULE_LICENSE("GPL v2");
>> diff --git a/drivers/platform/x86/amd/hsmp/hsmp.h b/drivers/platform/x86/amd/hsmp/hsmp.h
>> index 9c5b9c263fc1..9ab50bc74676 100644
>> --- a/drivers/platform/x86/amd/hsmp/hsmp.h
>> +++ b/drivers/platform/x86/amd/hsmp/hsmp.h
>> @@ -52,7 +52,6 @@ struct hsmp_plat_device {
>>        struct hsmp_socket *sock;
>>        u32 proto_ver;
>>        u16 num_sockets;
>> -     bool is_acpi_device;
>>        bool is_probed;
>>   };
>>
>> @@ -61,14 +60,13 @@ extern struct hsmp_plat_device hsmp_pdev;
>>   ssize_t hsmp_metric_tbl_read(struct file *filp, struct kobject *kobj,
>>                             struct bin_attribute *bin_attr, char *buf,
>>                             loff_t off, size_t count);
>> -int hsmp_create_non_acpi_sysfs_if(struct device *dev);
>> -int hsmp_create_acpi_sysfs_if(struct device *dev);
>>   int hsmp_cache_proto_ver(u16 sock_ind);
>>   umode_t hsmp_is_sock_attr_visible(struct kobject *kobj,
>>                                  struct bin_attribute *battr, int id);
>>   int hsmp_create_attr_list(struct attribute_group *attr_grp,
>>                          struct device *dev, u16 sock_ind);
>>   int hsmp_test(u16 sock_ind, u32 value);
>> -int init_platform_device(struct device *dev);
>> -int init_acpi(struct device *dev);
>> +long hsmp_ioctl(struct file *fp, unsigned int cmd, unsigned long arg);
>> +void hsmp_misc_deregister(void);
>> +int hsmp_misc_register(struct device *dev);
>>   #endif /* HSMP_H */
>> diff --git a/drivers/platform/x86/amd/hsmp/plat.c b/drivers/platform/x86/amd/hsmp/plat.c
>> index e18cf82478a0..e49b53f8c5e3 100644
>> --- a/drivers/platform/x86/amd/hsmp/plat.c
>> +++ b/drivers/platform/x86/amd/hsmp/plat.c
>> @@ -12,11 +12,16 @@
>>   #include <asm/amd_nb.h>
>>
>>   #include <linux/device.h>
>> +#include <linux/module.h>
>>   #include <linux/pci.h>
>> +#include <linux/platform_device.h>
>>   #include <linux/sysfs.h>
>>
>>   #include "hsmp.h"
>>
>> +#define DRIVER_NAME          "amd_hsmp"
>> +#define DRIVER_VERSION               "2.3"
>> +
>>   /*
>>    * To access specific HSMP mailbox register, s/w writes the SMN address of HSMP mailbox
>>    * register into the SMN_INDEX register, and reads/writes the SMN_DATA reg.
>> @@ -50,7 +55,13 @@ static int amd_hsmp_pci_rdwr(struct hsmp_socket *sock, u32 offset,
>>        return ret;
>>   }
>>
>> -int hsmp_create_non_acpi_sysfs_if(struct device *dev)
>> +static const struct file_operations hsmp_fops = {
>> +     .owner          = THIS_MODULE,
>> +     .unlocked_ioctl = hsmp_ioctl,
>> +     .compat_ioctl   = hsmp_ioctl,
>> +};
>> +
>> +static int hsmp_create_non_acpi_sysfs_if(struct device *dev)
>>   {
>>        const struct attribute_group **hsmp_attr_grps;
>>        struct attribute_group *attr_grp;
>> @@ -88,7 +99,7 @@ static inline bool is_f1a_m0h(void)
>>        return false;
>>   }
>>
>> -int init_platform_device(struct device *dev)
>> +static int init_platform_device(struct device *dev)
>>   {
>>        struct hsmp_socket *sock;
>>        int ret, i;
>> @@ -134,3 +145,132 @@ int init_platform_device(struct device *dev)
>>
>>        return 0;
>>   }
>> +
>> +static int hsmp_pltdrv_probe(struct platform_device *pdev)
>> +{
>> +     int ret;
>> +
>> +     hsmp_pdev.sock = devm_kcalloc(&pdev->dev, hsmp_pdev.num_sockets,
>> +                                   sizeof(*hsmp_pdev.sock),
>> +                                   GFP_KERNEL);
>> +     if (!hsmp_pdev.sock)
>> +             return -ENOMEM;
>> +
>> +     ret = init_platform_device(&pdev->dev);
>> +     if (ret) {
>> +             dev_err(&pdev->dev, "Failed to init HSMP mailbox\n");
>> +             return ret;
>> +     }
>> +
>> +     ret = hsmp_create_non_acpi_sysfs_if(&pdev->dev);
>> +     if (ret)
>> +             dev_err(&pdev->dev, "Failed to create HSMP sysfs interface\n");
>> +
>> +     return hsmp_misc_register(&pdev->dev);
>> +}
>> +
>> +static void hsmp_pltdrv_remove(struct platform_device *pdev)
>> +{
>> +     hsmp_misc_deregister();
>> +}
>> +
>> +static struct platform_driver amd_hsmp_driver = {
>> +     .probe          = hsmp_pltdrv_probe,
>> +     .remove_new     = hsmp_pltdrv_remove,
>> +     .driver         = {
>> +             .name   = DRIVER_NAME,
>> +     },
>> +};
>> +
>> +static struct platform_device *amd_hsmp_platdev;
>> +
>> +static int hsmp_plat_dev_register(void)
>> +{
>> +     int ret;
>> +
>> +     amd_hsmp_platdev = platform_device_alloc(DRIVER_NAME, PLATFORM_DEVID_NONE);
>> +     if (!amd_hsmp_platdev)
>> +             return -ENOMEM;
>> +
>> +     ret = platform_device_add(amd_hsmp_platdev);
>> +     if (ret)
>> +             platform_device_put(amd_hsmp_platdev);
>> +
>> +     return ret;
>> +}
>> +
>> +/*
>> + * This check is only needed for backward compatibility of previous platforms.
>> + * All new platforms are expected to support ACPI based probing.
>> + */
>> +static bool legacy_hsmp_support(void)
>> +{
>> +     if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD)
>> +             return false;
>> +
>> +     switch (boot_cpu_data.x86) {
>> +     case 0x19:
>> +             switch (boot_cpu_data.x86_model) {
>> +             case 0x00 ... 0x1F:
>> +             case 0x30 ... 0x3F:
>> +             case 0x90 ... 0x9F:
>> +             case 0xA0 ... 0xAF:
>> +                     return true;
>> +             default:
>> +                     return false;
>> +             }
>> +     case 0x1A:
>> +             switch (boot_cpu_data.x86_model) {
>> +             case 0x00 ... 0x1F:
>> +                     return true;
>> +             default:
>> +                     return false;
>> +             }
>> +     default:
>> +             return false;
>> +     }
>> +
>> +     return false;
>> +}
>> +
>> +static int __init hsmp_plt_init(void)
>> +{
>> +     int ret = -ENODEV;
>> +
>> +     if (!legacy_hsmp_support()) {
>> +             pr_info("HSMP is not supported on Family:%x model:%x\n",
>> +                     boot_cpu_data.x86, boot_cpu_data.x86_model);
>> +             return ret;
>> +     }
>> +
>> +     /*
>> +      * amd_nb_num() returns number of SMN/DF interfaces present in the system
>> +      * if we have N SMN/DF interfaces that ideally means N sockets
>> +      */
>> +     hsmp_pdev.num_sockets = amd_nb_num();
>> +     if (hsmp_pdev.num_sockets == 0 || hsmp_pdev.num_sockets > MAX_AMD_SOCKETS)
>> +             return ret;
>> +
>> +     ret = platform_driver_register(&amd_hsmp_driver);
>> +     if (ret)
>> +             return ret;
>> +
>> +     ret = hsmp_plat_dev_register();
>> +     if (ret)
>> +             platform_driver_unregister(&amd_hsmp_driver);
>> +
>> +     return ret;
>> +}
>> +
>> +static void __exit hsmp_plt_exit(void)
>> +{
>> +     platform_device_unregister(amd_hsmp_platdev);
>> +     platform_driver_unregister(&amd_hsmp_driver);
>> +}
>> +
>> +device_initcall(hsmp_plt_init);
>> +module_exit(hsmp_plt_exit);
>> +
>> +MODULE_DESCRIPTION("AMD HSMP Platform Interface Driver");
>> +MODULE_VERSION(DRIVER_VERSION);
>> +MODULE_LICENSE("GPL");