diff mbox series

[v2,2/2] PCI: hotplug: Add extension driver for Ampere Altra hotplug LED control

Message ID 20230930002036.6491-2-scott@os.amperecomputing.com
State New
Headers
Series [v2,1/2] PCI: acpiphp: Allow built-in attention drivers |

Commit Message

D Scott Phillips Sept. 30, 2023, 12:20 a.m. UTC 
  On Ampere Altra, PCIe hotplug is handled through ACPI. A side interface is
also present to request system firmware control of attention LEDs. Add an
ACPI PCI Hotplug companion driver to support attention LED control.

Signed-off-by: D Scott Phillips <scott@os.amperecomputing.com>
---
Changes since v1:
- remove build-as-module restriction
- add some more description
- don't open code PCI_SLOT()
- convert to a platform driver

 drivers/pci/hotplug/Kconfig                |  12 ++
 drivers/pci/hotplug/Makefile               |   1 +
 drivers/pci/hotplug/acpiphp_ampere_altra.c | 127 +++++++++++++++++++++
 3 files changed, 140 insertions(+)
 create mode 100644 drivers/pci/hotplug/acpiphp_ampere_altra.c

Comments

Rafael J. Wysocki Oct. 3, 2023, 6:32 p.m. UTC | #1 
On Sat, Sep 30, 2023 at 2:20 AM D Scott Phillips
<scott@os.amperecomputing.com> wrote:
>
> On Ampere Altra, PCIe hotplug is handled through ACPI. A side interface is
> also present to request system firmware control of attention LEDs. Add an
> ACPI PCI Hotplug companion driver to support attention LED control.
>
> Signed-off-by: D Scott Phillips <scott@os.amperecomputing.com>

Acked-by: Rafael J. Wysocki <rafael@kernel.org>

for the probing part.

> ---
> Changes since v1:
> - remove build-as-module restriction
> - add some more description
> - don't open code PCI_SLOT()
> - convert to a platform driver
>
>  drivers/pci/hotplug/Kconfig                |  12 ++
>  drivers/pci/hotplug/Makefile               |   1 +
>  drivers/pci/hotplug/acpiphp_ampere_altra.c | 127 +++++++++++++++++++++
>  3 files changed, 140 insertions(+)
>  create mode 100644 drivers/pci/hotplug/acpiphp_ampere_altra.c
>
> diff --git a/drivers/pci/hotplug/Kconfig b/drivers/pci/hotplug/Kconfig
> index 48113b210cf93..1472aef0fb812 100644
> --- a/drivers/pci/hotplug/Kconfig
> +++ b/drivers/pci/hotplug/Kconfig
> @@ -61,6 +61,18 @@ config HOTPLUG_PCI_ACPI
>
>           When in doubt, say N.
>
> +config HOTPLUG_PCI_ACPI_AMPERE_ALTRA
> +       tristate "ACPI PCI Hotplug driver Ampere Altra extensions"
> +       depends on HOTPLUG_PCI_ACPI
> +       depends on HAVE_ARM_SMCCC_DISCOVERY
> +       help
> +         Say Y here if you have an Ampere Altra system.
> +
> +         To compile this driver as a module, choose M here: the
> +         module will be called acpiphp_ampere_altra.
> +
> +         When in doubt, say N.
> +
>  config HOTPLUG_PCI_ACPI_IBM
>         tristate "ACPI PCI Hotplug driver IBM extensions"
>         depends on HOTPLUG_PCI_ACPI
> diff --git a/drivers/pci/hotplug/Makefile b/drivers/pci/hotplug/Makefile
> index 5196983220df6..240c99517d5e9 100644
> --- a/drivers/pci/hotplug/Makefile
> +++ b/drivers/pci/hotplug/Makefile
> @@ -23,6 +23,7 @@ obj-$(CONFIG_HOTPLUG_PCI_S390)                += s390_pci_hpc.o
>
>  # acpiphp_ibm extends acpiphp, so should be linked afterwards.
>
> +obj-$(CONFIG_HOTPLUG_PCI_ACPI_AMPERE_ALTRA)    += acpiphp_ampere_altra.o
>  obj-$(CONFIG_HOTPLUG_PCI_ACPI_IBM)     += acpiphp_ibm.o
>
>  pci_hotplug-objs       :=      pci_hotplug_core.o
> diff --git a/drivers/pci/hotplug/acpiphp_ampere_altra.c b/drivers/pci/hotplug/acpiphp_ampere_altra.c
> new file mode 100644
> index 0000000000000..1b1fe5d6a3fbf
> --- /dev/null
> +++ b/drivers/pci/hotplug/acpiphp_ampere_altra.c
> @@ -0,0 +1,127 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * ACPI PCI Hot Plug Extension for Ampere Altra. Allows control of
> + * attention LEDs via requests to system firmware.
> + *
> + * Copyright (C) 2023 Ampere Computing LLC
> + */
> +
> +#define pr_fmt(fmt) "acpiphp_ampere_altra: " fmt
> +
> +#include <linux/init.h>
> +#include <linux/module.h>
> +#include <linux/pci.h>
> +#include <linux/pci_hotplug.h>
> +#include <linux/platform_device.h>
> +
> +#include "acpiphp.h"
> +
> +#define HANDLE_OPEN    0xb0200000
> +#define HANDLE_CLOSE   0xb0300000
> +#define REQUEST                0xf0700000
> +#define LED_CMD                0x00000004
> +#define LED_ATTENTION  0x00000002
> +#define LED_SET_ON     0x00000001
> +#define LED_SET_OFF    0x00000002
> +#define LED_SET_BLINK  0x00000003
> +
> +static u32 led_service_id[4];
> +
> +static int led_status(u8 status)
> +{
> +       switch (status) {
> +       case 1: return LED_SET_ON;
> +       case 2: return LED_SET_BLINK;
> +       default: return LED_SET_OFF;
> +       }
> +}
> +
> +static int set_attention_status(struct hotplug_slot *slot, u8 status)
> +{
> +       struct arm_smccc_res res;
> +       struct pci_bus *bus;
> +       struct pci_dev *root_port;
> +       unsigned long flags;
> +       u32 handle;
> +       int ret = 0;
> +
> +       bus = slot->pci_slot->bus;
> +       root_port = pcie_find_root_port(bus->self);
> +       if (!root_port)
> +               return -ENODEV;
> +
> +       local_irq_save(flags);
> +       arm_smccc_smc(HANDLE_OPEN, led_service_id[0], led_service_id[1],
> +                     led_service_id[2], led_service_id[3], 0, 0, 0, &res);
> +       if (res.a0) {
> +               ret = -ENODEV;
> +               goto out;
> +       }
> +       handle = res.a1 & 0xffff0000;
> +
> +       arm_smccc_smc(REQUEST, LED_CMD, led_status(status), LED_ATTENTION,
> +                     pci_domain_nr(bus) | (PCI_SLOT(root_port->devfn) << 4), 0, 0,
> +                     handle, &res);
> +       if (res.a0)
> +               ret = -ENODEV;
> +
> +       arm_smccc_smc(HANDLE_CLOSE, handle, 0, 0, 0, 0, 0, 0, &res);
> +
> + out:
> +       local_irq_restore(flags);
> +       return ret;
> +}
> +
> +static int get_attention_status(struct hotplug_slot *slot, u8 *status)
> +{
> +       return -EINVAL;
> +}
> +
> +static struct acpiphp_attention_info ampere_altra_attn = {
> +       .set_attn = set_attention_status,
> +       .get_attn = get_attention_status,
> +       .owner = THIS_MODULE,
> +};
> +
> +static int altra_led_probe(struct platform_device *pdev)
> +{
> +       struct fwnode_handle *fwnode = dev_fwnode(&pdev->dev);
> +       int ret;
> +
> +       ret = fwnode_property_read_u32_array(fwnode, "uuid", led_service_id, 4);
> +       if (ret) {
> +               dev_err(&pdev->dev, "can't find uuid\n");
> +               return ret;
> +       }
> +
> +       ret = acpiphp_register_attention(&ampere_altra_attn);
> +       if (ret) {
> +               dev_err(&pdev->dev, "can't register driver\n");
> +               return ret;
> +       }
> +       return 0;
> +}
> +
> +static void altra_led_remove(struct platform_device *pdev)
> +{
> +       acpiphp_unregister_attention(&ampere_altra_attn);
> +}
> +
> +static const struct acpi_device_id altra_led_ids[] = {
> +       { "AMPC0008", 0 },
> +       { }
> +};
> +MODULE_DEVICE_TABLE(acpi, altra_led_ids);
> +
> +static struct platform_driver altra_led_driver = {
> +       .driver = {
> +               .name = "ampere-altra-leds",
> +               .acpi_match_table = altra_led_ids,
> +       },
> +       .probe = altra_led_probe,
> +       .remove_new = altra_led_remove,
> +};
> +module_platform_driver(altra_led_driver);
> +
> +MODULE_AUTHOR("D Scott Phillips <scott@os.amperecomputing.com>");
> +MODULE_LICENSE("GPL");
> --
> 2.41.0
>
Bjorn Helgaas Oct. 25, 2023, 5:22 p.m. UTC | #2 
On Fri, Sep 29, 2023 at 05:20:36PM -0700, D Scott Phillips wrote:
> On Ampere Altra, PCIe hotplug is handled through ACPI. A side interface is
> also present to request system firmware control of attention LEDs. Add an
> ACPI PCI Hotplug companion driver to support attention LED control.
> ...

> +	arm_smccc_smc(REQUEST, LED_CMD, led_status(status), LED_ATTENTION,
> +		      pci_domain_nr(bus) | (PCI_SLOT(root_port->devfn) << 4), 0, 0,

pci_domain_nr() returns "int" (normally 32 bits), but since this is an
ACPI system, the domain comes from _SEG, which is defined to be 16
bits (ACPI r6.5, sec 6.5.6).

So it looks like ORing in the "slot << 4" clobbers the upper 12 bits
of _SEG.

Is this code doing the right thing?
D Scott Phillips Oct. 25, 2023, 5:41 p.m. UTC | #3 
Bjorn Helgaas <helgaas@kernel.org> writes:

> On Fri, Sep 29, 2023 at 05:20:36PM -0700, D Scott Phillips wrote:
>> On Ampere Altra, PCIe hotplug is handled through ACPI. A side interface is
>> also present to request system firmware control of attention LEDs. Add an
>> ACPI PCI Hotplug companion driver to support attention LED control.
>> ...
>
>> +	arm_smccc_smc(REQUEST, LED_CMD, led_status(status), LED_ATTENTION,
>> +		      pci_domain_nr(bus) | (PCI_SLOT(root_port->devfn) << 4), 0, 0,
>
> pci_domain_nr() returns "int" (normally 32 bits), but since this is an
> ACPI system, the domain comes from _SEG, which is defined to be 16
> bits (ACPI r6.5, sec 6.5.6).
>
> So it looks like ORing in the "slot << 4" clobbers the upper 12 bits
> of _SEG.
>
> Is this code doing the right thing?

Hi Bjorn,

on these Altra platforms _SEG is limited within 0-11. I can add an `&
0xf` to pci_domain_nr() to make it clear that the segment number is
encoded down into 4 bits in the smc request.
Bjorn Helgaas Oct. 25, 2023, 6:06 p.m. UTC | #4 
On Wed, Oct 25, 2023 at 10:41:46AM -0700, D Scott Phillips wrote:
> Bjorn Helgaas <helgaas@kernel.org> writes:
> 
> > On Fri, Sep 29, 2023 at 05:20:36PM -0700, D Scott Phillips wrote:
> >> On Ampere Altra, PCIe hotplug is handled through ACPI. A side interface is
> >> also present to request system firmware control of attention LEDs. Add an
> >> ACPI PCI Hotplug companion driver to support attention LED control.
> >> ...
> >
> >> +	arm_smccc_smc(REQUEST, LED_CMD, led_status(status), LED_ATTENTION,
> >> +		      pci_domain_nr(bus) | (PCI_SLOT(root_port->devfn) << 4), 0, 0,
> >
> > pci_domain_nr() returns "int" (normally 32 bits), but since this is an
> > ACPI system, the domain comes from _SEG, which is defined to be 16
> > bits (ACPI r6.5, sec 6.5.6).
> >
> > So it looks like ORing in the "slot << 4" clobbers the upper 12 bits
> > of _SEG.
> >
> > Is this code doing the right thing?
> 
> Hi Bjorn,
> 
> on these Altra platforms _SEG is limited within 0-11. I can add an `&
> 0xf` to pci_domain_nr() to make it clear that the segment number is
> encoded down into 4 bits in the smc request.

If the following looks OK, we're all set.  I put these on pci/hotplug
for v6.7, thanks!

+static int set_attention_status(struct hotplug_slot *slot, u8 status)
+{
+	struct arm_smccc_res res;
+	struct pci_bus *bus;
+	struct pci_dev *root_port;
+	unsigned long flags;
+	u32 handle;
+	int ret = 0;
+
+	bus = slot->pci_slot->bus;
+	root_port = pcie_find_root_port(bus->self);
+	if (!root_port)
+		return -ENODEV;
+
+	local_irq_save(flags);
+	arm_smccc_smc(HANDLE_OPEN, led_service_id[0], led_service_id[1],
+		      led_service_id[2], led_service_id[3], 0, 0, 0, &res);
+	if (res.a0) {
+		ret = -ENODEV;
+		goto out;
+	}
+	handle = res.a1 & 0xffff0000;
+
+	arm_smccc_smc(REQUEST, LED_CMD, led_status(status), LED_ATTENTION,
+		     PCI_SLOT(root_port->devfn) << 4 | pci_domain_nr(bus) & 0xf,
+		     0, 0, handle, &res);
+	if (res.a0)
+		ret = -ENODEV;
+
+	arm_smccc_smc(HANDLE_CLOSE, handle, 0, 0, 0, 0, 0, 0, &res);
+
+ out:
+	local_irq_restore(flags);
+	return ret;
+}
Anders Roxell Oct. 26, 2023, 10:47 a.m. UTC | #5 
On 2023-10-25 13:06, Bjorn Helgaas wrote:
> On Wed, Oct 25, 2023 at 10:41:46AM -0700, D Scott Phillips wrote:
> > Bjorn Helgaas <helgaas@kernel.org> writes:
> > 
> > > On Fri, Sep 29, 2023 at 05:20:36PM -0700, D Scott Phillips wrote:
> > >> On Ampere Altra, PCIe hotplug is handled through ACPI. A side interface is
> > >> also present to request system firmware control of attention LEDs. Add an
> > >> ACPI PCI Hotplug companion driver to support attention LED control.
> > >> ...
> > >
> > >> +	arm_smccc_smc(REQUEST, LED_CMD, led_status(status), LED_ATTENTION,
> > >> +		      pci_domain_nr(bus) | (PCI_SLOT(root_port->devfn) << 4), 0, 0,
> > >
> > > pci_domain_nr() returns "int" (normally 32 bits), but since this is an
> > > ACPI system, the domain comes from _SEG, which is defined to be 16
> > > bits (ACPI r6.5, sec 6.5.6).
> > >
> > > So it looks like ORing in the "slot << 4" clobbers the upper 12 bits
> > > of _SEG.
> > >
> > > Is this code doing the right thing?
> > 
> > Hi Bjorn,
> > 
> > on these Altra platforms _SEG is limited within 0-11. I can add an `&
> > 0xf` to pci_domain_nr() to make it clear that the segment number is
> > encoded down into 4 bits in the smc request.
> 
> If the following looks OK, we're all set.  I put these on pci/hotplug
> for v6.7, thanks!
> 
> +static int set_attention_status(struct hotplug_slot *slot, u8 status)
> +{
> +	struct arm_smccc_res res;
> +	struct pci_bus *bus;
> +	struct pci_dev *root_port;
> +	unsigned long flags;
> +	u32 handle;
> +	int ret = 0;
> +
> +	bus = slot->pci_slot->bus;
> +	root_port = pcie_find_root_port(bus->self);
> +	if (!root_port)
> +		return -ENODEV;
> +
> +	local_irq_save(flags);
> +	arm_smccc_smc(HANDLE_OPEN, led_service_id[0], led_service_id[1],
> +		      led_service_id[2], led_service_id[3], 0, 0, 0, &res);
> +	if (res.a0) {
> +		ret = -ENODEV;
> +		goto out;
> +	}
> +	handle = res.a1 & 0xffff0000;
> +
> +	arm_smccc_smc(REQUEST, LED_CMD, led_status(status), LED_ATTENTION,
> +		     PCI_SLOT(root_port->devfn) << 4 | pci_domain_nr(bus) & 0xf,
> +		     0, 0, handle, &res);
> +	if (res.a0)
> +		ret = -ENODEV;
> +
> +	arm_smccc_smc(HANDLE_CLOSE, handle, 0, 0, 0, 0, 0, 0, &res);
> +
> + out:
> +	local_irq_restore(flags);
> +	return ret;
> +}

Hi,

Building todays linux-next tag next-20231026 for arm64 with
CONFIG_HOTPLUG_PCI_ACPI_AMPERE_ALTRA=m I see the following build error.

drivers/pci/hotplug/acpiphp_ampere_altra.c: In function 'set_attention_status':
drivers/pci/hotplug/acpiphp_ampere_altra.c:63:75: error: suggest parentheses around arithmetic in operand of '|' [-Werror=parentheses]
   63 |                      PCI_SLOT(root_port->devfn) << 4 | pci_domain_nr(bus) & 0xf,
      |                                                        ~~~~~~~~~~~~~~~~~~~^~~~~
include/linux/arm-smccc.h:382:44: note: in definition of macro 'arm_smccc_smc'
  382 | #define arm_smccc_smc(...) __arm_smccc_smc(__VA_ARGS__, NULL)
      |                                            ^~~~~~~~~~~
cc1: all warnings being treated as errors
make[6]: *** [scripts/Makefile.build:243: drivers/pci/hotplug/acpiphp_ampere_altra.o] Error 1

Looks like this is the problematic patch
13ba8a09c4f6 ("PCI: hotplug: Add Ampere Altra Attention Indicator extension driver")

Cheers,
Anders
Bjorn Helgaas Oct. 26, 2023, 11:04 a.m. UTC | #6 
On Thu, Oct 26, 2023 at 12:47:31PM +0200, Anders Roxell wrote:
> On 2023-10-25 13:06, Bjorn Helgaas wrote:
> > On Wed, Oct 25, 2023 at 10:41:46AM -0700, D Scott Phillips wrote:
> > > Bjorn Helgaas <helgaas@kernel.org> writes:
> > > 
> > > > On Fri, Sep 29, 2023 at 05:20:36PM -0700, D Scott Phillips wrote:
> > > >> On Ampere Altra, PCIe hotplug is handled through ACPI. A side interface is
> > > >> also present to request system firmware control of attention LEDs. Add an
> > > >> ACPI PCI Hotplug companion driver to support attention LED control.
> > > >> ...
> > > >
> > > >> +	arm_smccc_smc(REQUEST, LED_CMD, led_status(status), LED_ATTENTION,
> > > >> +		      pci_domain_nr(bus) | (PCI_SLOT(root_port->devfn) << 4), 0, 0,
> > > >
> > > > pci_domain_nr() returns "int" (normally 32 bits), but since this is an
> > > > ACPI system, the domain comes from _SEG, which is defined to be 16
> > > > bits (ACPI r6.5, sec 6.5.6).
> > > >
> > > > So it looks like ORing in the "slot << 4" clobbers the upper 12 bits
> > > > of _SEG.
> > > >
> > > > Is this code doing the right thing?
> > > 
> > > Hi Bjorn,
> > > 
> > > on these Altra platforms _SEG is limited within 0-11. I can add an `&
> > > 0xf` to pci_domain_nr() to make it clear that the segment number is
> > > encoded down into 4 bits in the smc request.
> > 
> > If the following looks OK, we're all set.  I put these on pci/hotplug
> > for v6.7, thanks!
> > 
> > +static int set_attention_status(struct hotplug_slot *slot, u8 status)
> > +{
> > +	struct arm_smccc_res res;
> > +	struct pci_bus *bus;
> > +	struct pci_dev *root_port;
> > +	unsigned long flags;
> > +	u32 handle;
> > +	int ret = 0;
> > +
> > +	bus = slot->pci_slot->bus;
> > +	root_port = pcie_find_root_port(bus->self);
> > +	if (!root_port)
> > +		return -ENODEV;
> > +
> > +	local_irq_save(flags);
> > +	arm_smccc_smc(HANDLE_OPEN, led_service_id[0], led_service_id[1],
> > +		      led_service_id[2], led_service_id[3], 0, 0, 0, &res);
> > +	if (res.a0) {
> > +		ret = -ENODEV;
> > +		goto out;
> > +	}
> > +	handle = res.a1 & 0xffff0000;
> > +
> > +	arm_smccc_smc(REQUEST, LED_CMD, led_status(status), LED_ATTENTION,
> > +		     PCI_SLOT(root_port->devfn) << 4 | pci_domain_nr(bus) & 0xf,
> > +		     0, 0, handle, &res);
> > +	if (res.a0)
> > +		ret = -ENODEV;
> > +
> > +	arm_smccc_smc(HANDLE_CLOSE, handle, 0, 0, 0, 0, 0, 0, &res);
> > +
> > + out:
> > +	local_irq_restore(flags);
> > +	return ret;
> > +}
> 
> Hi,
> 
> Building todays linux-next tag next-20231026 for arm64 with
> CONFIG_HOTPLUG_PCI_ACPI_AMPERE_ALTRA=m I see the following build error.
> 
> drivers/pci/hotplug/acpiphp_ampere_altra.c: In function 'set_attention_status':
> drivers/pci/hotplug/acpiphp_ampere_altra.c:63:75: error: suggest parentheses around arithmetic in operand of '|' [-Werror=parentheses]
>    63 |                      PCI_SLOT(root_port->devfn) << 4 | pci_domain_nr(bus) & 0xf,
>       |                                                        ~~~~~~~~~~~~~~~~~~~^~~~~
> include/linux/arm-smccc.h:382:44: note: in definition of macro 'arm_smccc_smc'
>   382 | #define arm_smccc_smc(...) __arm_smccc_smc(__VA_ARGS__, NULL)
>       |                                            ^~~~~~~~~~~
> cc1: all warnings being treated as errors
> make[6]: *** [scripts/Makefile.build:243: drivers/pci/hotplug/acpiphp_ampere_altra.o] Error 1

My fault, fixed.

Bjorn
diff mbox series

Patch

diff --git a/drivers/pci/hotplug/Kconfig b/drivers/pci/hotplug/Kconfig
index 48113b210cf93..1472aef0fb812 100644
--- a/drivers/pci/hotplug/Kconfig
+++ b/drivers/pci/hotplug/Kconfig
@@ -61,6 +61,18 @@  config HOTPLUG_PCI_ACPI
 
 	  When in doubt, say N.
 
+config HOTPLUG_PCI_ACPI_AMPERE_ALTRA
+	tristate "ACPI PCI Hotplug driver Ampere Altra extensions"
+	depends on HOTPLUG_PCI_ACPI
+	depends on HAVE_ARM_SMCCC_DISCOVERY
+	help
+	  Say Y here if you have an Ampere Altra system.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called acpiphp_ampere_altra.
+
+	  When in doubt, say N.
+
 config HOTPLUG_PCI_ACPI_IBM
 	tristate "ACPI PCI Hotplug driver IBM extensions"
 	depends on HOTPLUG_PCI_ACPI
diff --git a/drivers/pci/hotplug/Makefile b/drivers/pci/hotplug/Makefile
index 5196983220df6..240c99517d5e9 100644
--- a/drivers/pci/hotplug/Makefile
+++ b/drivers/pci/hotplug/Makefile
@@ -23,6 +23,7 @@  obj-$(CONFIG_HOTPLUG_PCI_S390)		+= s390_pci_hpc.o
 
 # acpiphp_ibm extends acpiphp, so should be linked afterwards.
 
+obj-$(CONFIG_HOTPLUG_PCI_ACPI_AMPERE_ALTRA)	+= acpiphp_ampere_altra.o
 obj-$(CONFIG_HOTPLUG_PCI_ACPI_IBM)	+= acpiphp_ibm.o
 
 pci_hotplug-objs	:=	pci_hotplug_core.o
diff --git a/drivers/pci/hotplug/acpiphp_ampere_altra.c b/drivers/pci/hotplug/acpiphp_ampere_altra.c
new file mode 100644
index 0000000000000..1b1fe5d6a3fbf
--- /dev/null
+++ b/drivers/pci/hotplug/acpiphp_ampere_altra.c
@@ -0,0 +1,127 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ACPI PCI Hot Plug Extension for Ampere Altra. Allows control of
+ * attention LEDs via requests to system firmware.
+ *
+ * Copyright (C) 2023 Ampere Computing LLC
+ */
+
+#define pr_fmt(fmt) "acpiphp_ampere_altra: " fmt
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/pci_hotplug.h>
+#include <linux/platform_device.h>
+
+#include "acpiphp.h"
+
+#define HANDLE_OPEN	0xb0200000
+#define HANDLE_CLOSE	0xb0300000
+#define REQUEST		0xf0700000
+#define LED_CMD		0x00000004
+#define LED_ATTENTION	0x00000002
+#define LED_SET_ON	0x00000001
+#define LED_SET_OFF	0x00000002
+#define LED_SET_BLINK	0x00000003
+
+static u32 led_service_id[4];
+
+static int led_status(u8 status)
+{
+	switch (status) {
+	case 1: return LED_SET_ON;
+	case 2: return LED_SET_BLINK;
+	default: return LED_SET_OFF;
+	}
+}
+
+static int set_attention_status(struct hotplug_slot *slot, u8 status)
+{
+	struct arm_smccc_res res;
+	struct pci_bus *bus;
+	struct pci_dev *root_port;
+	unsigned long flags;
+	u32 handle;
+	int ret = 0;
+
+	bus = slot->pci_slot->bus;
+	root_port = pcie_find_root_port(bus->self);
+	if (!root_port)
+		return -ENODEV;
+
+	local_irq_save(flags);
+	arm_smccc_smc(HANDLE_OPEN, led_service_id[0], led_service_id[1],
+		      led_service_id[2], led_service_id[3], 0, 0, 0, &res);
+	if (res.a0) {
+		ret = -ENODEV;
+		goto out;
+	}
+	handle = res.a1 & 0xffff0000;
+
+	arm_smccc_smc(REQUEST, LED_CMD, led_status(status), LED_ATTENTION,
+		      pci_domain_nr(bus) | (PCI_SLOT(root_port->devfn) << 4), 0, 0,
+		      handle, &res);
+	if (res.a0)
+		ret = -ENODEV;
+
+	arm_smccc_smc(HANDLE_CLOSE, handle, 0, 0, 0, 0, 0, 0, &res);
+
+ out:
+	local_irq_restore(flags);
+	return ret;
+}
+
+static int get_attention_status(struct hotplug_slot *slot, u8 *status)
+{
+	return -EINVAL;
+}
+
+static struct acpiphp_attention_info ampere_altra_attn = {
+	.set_attn = set_attention_status,
+	.get_attn = get_attention_status,
+	.owner = THIS_MODULE,
+};
+
+static int altra_led_probe(struct platform_device *pdev)
+{
+	struct fwnode_handle *fwnode = dev_fwnode(&pdev->dev);
+	int ret;
+
+	ret = fwnode_property_read_u32_array(fwnode, "uuid", led_service_id, 4);
+	if (ret) {
+		dev_err(&pdev->dev, "can't find uuid\n");
+		return ret;
+	}
+
+	ret = acpiphp_register_attention(&ampere_altra_attn);
+	if (ret) {
+		dev_err(&pdev->dev, "can't register driver\n");
+		return ret;
+	}
+	return 0;
+}
+
+static void altra_led_remove(struct platform_device *pdev)
+{
+	acpiphp_unregister_attention(&ampere_altra_attn);
+}
+
+static const struct acpi_device_id altra_led_ids[] = {
+	{ "AMPC0008", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(acpi, altra_led_ids);
+
+static struct platform_driver altra_led_driver = {
+	.driver = {
+		.name = "ampere-altra-leds",
+		.acpi_match_table = altra_led_ids,
+	},
+	.probe = altra_led_probe,
+	.remove_new = altra_led_remove,
+};
+module_platform_driver(altra_led_driver);
+
+MODULE_AUTHOR("D Scott Phillips <scott@os.amperecomputing.com>");
+MODULE_LICENSE("GPL");