[PATCH v4 3/3] PCI/NPEM: Add _DSM PCIe SSD status LED management

[Mariusz Tkaczyk <mariusz.tkaczyk@linux.intel.com>]

Device Specific Method PCIe SSD Status LED Management (_DSM) defined in
PCI Firmware Spec r3.3 sec 4.7 provides a way to manage LEDs via ACPI.

The design is similar to NPEM defined in PCIe Base Specification r6.1
sec 6.28:
  - both standards are indication oriented,
  - _DSM supported bits are corresponding to NPEM capability
    register bits
  - _DSM control bits are corresponding to NPEM control register
    bits.

_DSM does not support enclosure specific indications and special NPEM
commands NPEM_ENABLE and NPEM_RESET.

_DSM is implemented as a second op in NPEM driver. The standard used
in background is not presented to user. The interface is accessed same
as NPEM.

According to spec, _DSM has higher priority and availability  of _DSM
in not limited to devices with NPEM support. It is followed in
implementation.

Link: https://members.pcisig.com/wg/PCI-SIG/document/14025
Link: https://members.pcisig.com/wg/PCI-SIG/document/15350
Suggested-by: Lukas Wunner <lukas@wunner.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Tested-by: Stuart Hayes <stuart.w.hayes@gmail.com>
Signed-off-by: Stuart Hayes <stuart.w.hayes@gmail.com>
Signed-off-by: Mariusz Tkaczyk <mariusz.tkaczyk@linux.intel.com>
---
 drivers/pci/npem.c | 147 ++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 144 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/npem.c b/drivers/pci/npem.c
index 3aa0b6e94cbd..fb427e68d107 100644
--- a/drivers/pci/npem.c
+++ b/drivers/pci/npem.c
@@ -11,6 +11,14 @@
  *	PCIe Base Specification r6.1 sec 6.28
  *	PCIe Base Specification r6.1 sec 7.9.19
  *
+ * _DSM Definitions for PCIe SSD Status LED
+ *	 PCI Firmware Specification, r3.3 sec 4.7
+ *
+ * Two backends are supported to manipulate indications:  Direct NPEM register
+ * access (npem_ops) and indirect access through the ACPI _DSM (dsm_ops).
+ * _DSM is used if supported, else NPEM.
+ *
+ * Copyright (c) 2021-2022 Dell Inc.
  * Copyright (c) 2023-2024 Intel Corporation
  *	Mariusz Tkaczyk <mariusz.tkaczyk@linux.intel.com>
  */
@@ -55,6 +63,21 @@ static const struct indication npem_indications[] = {
 	{0,			NULL}
 };
 
+/* _DSM PCIe SSD LED States are corresponding to NPEM register values */
+static const struct indication dsm_indications[] = {
+	{PCI_NPEM_IND_OK,	"enclosure:ok"},
+	{PCI_NPEM_IND_LOCATE,	"enclosure:locate"},
+	{PCI_NPEM_IND_FAIL,	"enclosure:fail"},
+	{PCI_NPEM_IND_REBUILD,	"enclosure:rebuild"},
+	{PCI_NPEM_IND_PFA,	"enclosure:pfa"},
+	{PCI_NPEM_IND_HOTSPARE,	"enclosure:hotspare"},
+	{PCI_NPEM_IND_ICA,	"enclosure:ica"},
+	{PCI_NPEM_IND_IFA,	"enclosure:ifa"},
+	{PCI_NPEM_IND_IDT,	"enclosure:idt"},
+	{PCI_NPEM_IND_DISABLED,	"enclosure:disabled"},
+	{0,			NULL}
+};
+
 #define for_each_indication(ind, inds) \
 	for (ind = inds; ind->bit; ind++)
 
@@ -252,6 +275,120 @@ static bool npem_has_dsm(struct pci_dev *pdev)
 			      BIT(GET_STATE_DSM) | BIT(SET_STATE_DSM));
 }
 
+struct dsm_output {
+	u16 status;
+	u8 function_specific_err;
+	u8 vendor_specific_err;
+	u32 state;
+};
+
+/**
+ * dsm_evaluate() - send DSM PCIe SSD Status LED command
+ * @pdev: PCI device
+ * @dsm_func: DSM LED Function
+ * @output: buffer to copy DSM Response
+ * @value_to_set: value for SET_STATE_DSM function
+ *
+ * To not bother caller with ACPI context, the returned _DSM Output Buffer is
+ * copied.
+ */
+static int dsm_evaluate(struct pci_dev *pdev, u64 dsm_func,
+			struct dsm_output *output, u32 value_to_set)
+{
+	acpi_handle handle = ACPI_HANDLE(&pdev->dev);
+	union acpi_object *out_obj, arg3[2];
+	union acpi_object *arg3_p = NULL;
+
+	if (dsm_func == SET_STATE_DSM) {
+		arg3[0].type = ACPI_TYPE_PACKAGE;
+		arg3[0].package.count = 1;
+		arg3[0].package.elements = &arg3[1];
+
+		arg3[1].type = ACPI_TYPE_BUFFER;
+		arg3[1].buffer.length = 4;
+		arg3[1].buffer.pointer = (u8 *)&value_to_set;
+
+		arg3_p = arg3;
+	}
+
+	out_obj = acpi_evaluate_dsm_typed(handle, &dsm_guid, 0x1, dsm_func,
+					  arg3_p, ACPI_TYPE_BUFFER);
+	if (!out_obj)
+		return -EIO;
+
+	if (out_obj->buffer.length < sizeof(struct dsm_output)) {
+		ACPI_FREE(out_obj);
+		return -EIO;
+	}
+
+	memcpy(output, out_obj->buffer.pointer, sizeof(struct dsm_output));
+
+	ACPI_FREE(out_obj);
+	return 0;
+}
+
+static int dsm_get(struct pci_dev *pdev, u64 dsm_func, u32 *buf)
+{
+	struct dsm_output output;
+	int ret = dsm_evaluate(pdev, dsm_func, &output, 0);
+
+	if (ret)
+		return ret;
+
+	if (output.status != 0)
+		return -EIO;
+
+	*buf = output.state;
+	return 0;
+}
+
+static int dsm_get_active_indications(struct npem *npem, u32 *buf)
+{
+	int ret = dsm_get(npem->dev, GET_STATE_DSM, buf);
+
+	/* Filter out not supported indications in response */
+	*buf &= npem->supported_indications;
+	return ret;
+}
+
+static int dsm_set_active_indications(struct npem *npem, u32 value)
+{
+	struct dsm_output output;
+	int ret = dsm_evaluate(npem->dev, SET_STATE_DSM, &output, value);
+
+	if (ret)
+		return ret;
+
+	switch (output.status) {
+	case 4:
+		/*
+		 * Not all bits are set. If this bit is set, the platform
+		 * disregarded some or all of the request state changes. OSPM
+		 * should check the resulting PCIe SSD Status LED States to see
+		 * what, if anything, has changed.
+		 *
+		 * PCI Firmware Specification, r3.3 Table 4-19.
+		 */
+		if (output.function_specific_err != 1)
+			return -EIO;
+		fallthrough;
+	case 0:
+		break;
+	default:
+		return -EIO;
+	}
+
+	npem->active_indications = output.state;
+
+	return 0;
+}
+
+static const struct npem_ops dsm_ops = {
+	.inds = dsm_indications,
+	.get_active_indications = dsm_get_active_indications,
+	.set_active_indications = dsm_set_active_indications,
+};
+
 static int npem_initialize_active_indications(struct npem *npem)
 {
 	int ret;
@@ -439,11 +576,15 @@ void pci_npem_create(struct pci_dev *dev)
 		 * OS should use the DSM for LED control if it is available
 		 * PCI Firmware Spec r3.3 sec 4.7.
 		 */
-		return;
+		ret = dsm_get(dev, GET_SUPPORTED_STATES_DSM, &cap);
+		if (ret)
+			return;
+
+		ops = &dsm_ops;
 	}
 
 	ret = pci_npem_init(dev, ops, pos, cap);
 	if (ret)
-		pci_err(dev, "Failed to register PCIe Enclosure Management driver, err: %d\n",
-			ret);
+		pci_err(dev, "Failed to register %s PCIe Enclosure Management driver, err: %d\n",
+			(ops == &dsm_ops ? "_DSM" : "Native"), ret);
 }
-- 
2.35.3