platforms/astbmc/witherspoon: Implement OpenCAPI support

OpenCAPI on Witherspoon is slightly more involved than on Zaius and ZZ, due
to the OpenCAPI links using the SXM2 connectors that are used for NVLink
GPUs.

This patch adds the regular OpenCAPI platform information, and also a
Witherspoon-specific presence detection callback that uses the previously
added OCC GPU presence detection to figure out the device types plugged
into each SXM2 socket.

The SXM2 connectors are capable of carrying 2 OpenCAPI links, and future
OpenCAPI devices are expected to make use of this. However, we don't yet
support ganged links and the various implications that has for handling
things like device reset, so for now, we only enable 1 brick per device.

Signed-off-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Acked-by: Reza Arbab <arbab@linux.ibm.com>
Reviewed-by: Alistair Popple <alistair@popple.id.au>
Reviewed-by: Frederic Barrat <fbarrat@linux.ibm.com>
Signed-off-by: Stewart Smith <stewart@linux.ibm.com>

1 files changed, 202 insertions, 3 deletions

diff --git a/platforms/astbmc/witherspoon.c b/platforms/astbmc/witherspoon.c
index ce83ff9..77a01d2 100644
--- a/platforms/astbmc/witherspoon.c
+++ b/platforms/astbmc/witherspoon.c
@@ -28,10 +28,18 @@
 #include <pci-slot.h>
 #include <phb4.h>
 #include <npu2.h>
+#include <occ.h>
+#include <i2c.h>
 
 #include "astbmc.h"
 #include "ast.h"
 
+static enum {
+	WITHERSPOON_TYPE_UNKNOWN,
+	WITHERSPOON_TYPE_SEQUOIA,
+	WITHERSPOON_TYPE_REDBUD
+} witherspoon_type;
+
 /*
  * HACK: Hostboot doesn't export the correct data for the system VPD EEPROM
  *       for this system. So we need to work around it here.
@@ -50,8 +58,35 @@ static void vpd_dt_fixup(void)
 	}
 }
 
+static void witherspoon_create_ocapi_i2c_bus(void)
+{
+	struct dt_node *xscom, *i2cm, *i2c_bus;
+	prlog(PR_DEBUG, "OCAPI: Adding I2C bus device node for OCAPI reset\n");
+	dt_for_each_compatible(dt_root, xscom, "ibm,xscom") {
+		i2cm = dt_find_by_name(xscom, "i2cm@a1000");
+		if (!i2cm) {
+			prlog(PR_ERR, "OCAPI: Failed to add I2C bus device node\n");
+			continue;
+		}
+
+		if (dt_find_by_name(i2cm, "i2c-bus@4"))
+			continue;
+
+		i2c_bus = dt_new_addr(i2cm, "i2c-bus", 4);
+		dt_add_property_cells(i2c_bus, "reg", 4);
+		dt_add_property_cells(i2c_bus, "bus-frequency", 0x61a80);
+		dt_add_property_strings(i2c_bus, "compatible",
+					"ibm,opal-i2c", "ibm,power8-i2c-port",
+					"ibm,power9-i2c-port");
+	}
+}
+
 static bool witherspoon_probe(void)
 {
+	struct dt_node *np;
+	int highest_gpu_group_id = 0;
+	int gpu_group_id;
+
 	if (!dt_node_is_compatible(dt_root, "ibm,witherspoon"))
 		return false;
 
@@ -63,6 +98,26 @@ static bool witherspoon_probe(void)
 
 	vpd_dt_fixup();
 
+	witherspoon_create_ocapi_i2c_bus();
+
+	dt_for_each_compatible(dt_root, np, "ibm,npu-link") {
+		gpu_group_id = dt_prop_get_u32(np, "ibm,npu-group-id");
+		if (gpu_group_id > highest_gpu_group_id)
+			highest_gpu_group_id = gpu_group_id;
+	};
+
+	switch (highest_gpu_group_id) {
+	case 1:
+		witherspoon_type = WITHERSPOON_TYPE_REDBUD;
+		break;
+	case 2:
+		witherspoon_type = WITHERSPOON_TYPE_SEQUOIA;
+		break;
+	default:
+		witherspoon_type = WITHERSPOON_TYPE_UNKNOWN;
+		prlog(PR_NOTICE, "PLAT: Unknown Witherspoon variant detected\n");
+	}
+
 	return true;
 }
 
@@ -154,14 +209,157 @@ static void witherspoon_pre_pci_fixup(void)
 	phb4_pre_pci_fixup_witherspoon();
 }
 
-static void witherspoon_npu2_device_detect(struct npu2 *npu)
+static void set_link_details(struct npu2 *npu, uint32_t link_index,
+			     uint32_t brick_index, enum npu2_dev_type type)
 {
-        /* Stub until we implement real device detection */
+	struct npu2_dev *dev = NULL;
 	for (int i = 0; i < npu->total_devices; i++) {
-		npu->devices[i].type = NPU2_DEV_TYPE_NVLINK;
+		if (npu->devices[i].link_index == link_index) {
+			dev = &npu->devices[i];
+			break;
+		}
+	}
+	if (!dev) {
+		prlog(PR_ERR, "PLAT: Could not find NPU link index %d\n",
+		      link_index);
+		return;
 	}
+	dev->brick_index = brick_index;
+	dev->type = type;
 }
 
+static void witherspoon_npu2_device_detect(struct npu2 *npu)
+{
+	struct proc_chip *chip;
+	uint8_t state;
+	uint64_t i2c_port_id = 0;
+	char port_name[17];
+	struct dt_node *dn;
+	int rc;
+
+	bool gpu0_present, gpu1_present;
+
+	if (witherspoon_type != WITHERSPOON_TYPE_REDBUD) {
+		prlog(PR_DEBUG, "PLAT: Setting all NPU links to NVLink, OpenCAPI only supported on Redbud\n");
+	        for (int i = 0; i < npu->total_devices; i++) {
+			npu->devices[i].type = NPU2_DEV_TYPE_NVLINK;
+		}
+		return;
+	}
+	assert(npu->total_devices == 6);
+
+	chip = get_chip(npu->chip_id);
+
+	/* Find I2C port */
+	snprintf(port_name, sizeof(port_name), "p8_%08x_e%dp%d",
+		 chip->id, platform.ocapi->i2c_engine,
+		 platform.ocapi->i2c_port);
+	dt_for_each_compatible(dt_root, dn, "ibm,power9-i2c-port") {
+		if (streq(port_name, dt_prop_get(dn, "ibm,port-name"))) {
+			i2c_port_id = dt_prop_get_u32(dn, "ibm,opal-id");
+			break;
+		}
+	}
+
+	if (!i2c_port_id) {
+		prlog(PR_ERR, "PLAT: Could not find NPU presence I2C port\n");
+		return;
+	}
+
+	gpu0_present = occ_get_gpu_presence(chip, 0);
+	if (gpu0_present) {
+		prlog(PR_DEBUG, "PLAT: Chip %d GPU#0 slot present\n", chip->id);
+	}
+
+	gpu1_present = occ_get_gpu_presence(chip, 1);
+	if (gpu1_present) {
+		prlog(PR_DEBUG, "PLAT: Chip %d GPU#1 slot present\n", chip->id);
+	}
+
+	/* Set pins to input */
+	state = 0xff;
+	rc = i2c_request_send(i2c_port_id,
+			      platform.ocapi->i2c_presence_addr, SMBUS_WRITE, 3,
+			      1, &state, 1, 120);
+	if (rc)
+		goto i2c_failed;
+
+	/* Read the presence value */
+	state = 0x00;
+	rc = i2c_request_send(i2c_port_id,
+			      platform.ocapi->i2c_presence_addr, SMBUS_READ, 0,
+			      1, &state, 1, 120);
+	if (rc)
+		goto i2c_failed;
+
+	if (gpu0_present) {
+		if (state & (1 << 0)) {
+			prlog(PR_DEBUG, "PLAT: Chip %d GPU#0 is OpenCAPI\n",
+			      chip->id);
+			/*
+			 * On witherspoon, bricks 2 and 3 are connected to
+			 * the lanes matching links 1 and 0 in OpenCAPI mode.
+			 */
+			set_link_details(npu, 0, 3, NPU2_DEV_TYPE_OPENCAPI);
+			/* We current don't support using the second link */
+			set_link_details(npu, 1, 2, NPU2_DEV_TYPE_UNKNOWN);
+		} else {
+			prlog(PR_DEBUG, "PLAT: Chip %d GPU#0 is NVLink\n",
+			      chip->id);
+			set_link_details(npu, 0, 0, NPU2_DEV_TYPE_NVLINK);
+			set_link_details(npu, 1, 1, NPU2_DEV_TYPE_NVLINK);
+			set_link_details(npu, 2, 2, NPU2_DEV_TYPE_NVLINK);
+		}
+	}
+
+	if (gpu1_present) {
+		if (state & (1 << 1)) {
+			prlog(PR_DEBUG, "PLAT: Chip %d GPU#1 is OpenCAPI\n",
+			      chip->id);
+			set_link_details(npu, 4, 4, NPU2_DEV_TYPE_OPENCAPI);
+			/* We current don't support using the second link */
+			set_link_details(npu, 5, 5, NPU2_DEV_TYPE_UNKNOWN);
+		} else {
+			prlog(PR_DEBUG, "PLAT: Chip %d GPU#1 is NVLink\n",
+			      chip->id);
+			set_link_details(npu, 3, 3, NPU2_DEV_TYPE_NVLINK);
+			set_link_details(npu, 4, 4, NPU2_DEV_TYPE_NVLINK);
+			set_link_details(npu, 5, 5, NPU2_DEV_TYPE_NVLINK);
+		}
+	}
+
+	return;
+
+i2c_failed:
+	prlog(PR_ERR, "PLAT: NPU device type detection failed, rc=%d\n", rc);
+	return;
+}
+
+const struct platform_ocapi witherspoon_ocapi = {
+       .i2c_engine          = 1,
+       .i2c_port            = 4,
+       .odl_phy_swap        = false,
+       .i2c_reset_addr      = 0x20,
+       /*
+	* Witherspoon uses SXM2 connectors, carrying 2 OCAPI links
+	* over a single connector - hence each pair of bricks shares
+	* the same pin for resets. We currently only support using
+	* bricks 3 and 4, among other reasons because we can't handle
+	* a reset on one link causing the other link to reset as
+	* well.
+	*/
+       .i2c_reset_brick2    = 1 << 0,
+       .i2c_reset_brick3    = 1 << 0,
+       .i2c_reset_brick4    = 1 << 1,
+       .i2c_reset_brick5    = 1 << 1,
+       .i2c_presence_addr   = 0x20,
+       /* unused, we do this in custom presence detect */
+       .i2c_presence_brick2 = 0,
+       .i2c_presence_brick3 = 0,
+       .i2c_presence_brick4 = 0,
+       .i2c_presence_brick5 = 0,
+};
+
 /* The only difference between these is the PCI slot handling */
 
 DECLARE_PLATFORM(witherspoon) = {
@@ -179,5 +377,6 @@ DECLARE_PLATFORM(witherspoon) = {
 	.terminate		= ipmi_terminate,
 
 	.pci_get_slot_info	= dt_slot_get_slot_info,
+	.ocapi                  = &witherspoon_ocapi,
 	.npu2_device_detect	= witherspoon_npu2_device_detect,
 };