[PATCH net-next 3/4] ionic: add an auxiliary device for hardware monitoring

["Nikhil P. Rao" <nikhil.rao@amd.com>]

When the firmware sets IONIC_DEV_CAP_HWMON, create an "hwmon" auxiliary
device so the adapter's sensors can be exposed by a driver in
drivers/hwmon/ rather than by the Ethernet driver.

The GETCAPS response buffer belongs to ionic for the life of the device,
not to the hwmon driver, so a command abandoned on timeout or unbind can
only write into that buffer, never into freed memory.

Reviewed-by: Brett Creeley <brett.creeley@amd.com>
Signed-off-by: Nikhil P. Rao <nikhil.rao@amd.com>
---
 drivers/net/ethernet/pensando/ionic/ionic.h     |   2 +
 drivers/net/ethernet/pensando/ionic/ionic_aux.c | 109 ++++++++++++++++++++++++
 drivers/net/ethernet/pensando/ionic/ionic_lif.h |   1 +
 include/linux/ionic/ionic_hwmon.h               |  40 +++++++++
 4 files changed, 152 insertions(+)

diff --git a/drivers/net/ethernet/pensando/ionic/ionic.h b/drivers/net/ethernet/pensando/ionic/ionic.h
index 555a77db1b1e..814d70b8623b 100644
--- a/drivers/net/ethernet/pensando/ionic/ionic.h
+++ b/drivers/net/ethernet/pensando/ionic/ionic.h
@@ -64,6 +64,8 @@ struct ionic {
 	int num_vfs;
 	struct timer_list watchdog_timer;
 	int watchdog_period;
+	void *hwmon_caps_buf;
+	dma_addr_t hwmon_caps_pa;
 };
 
 int ionic_adminq_post(struct ionic_lif *lif, struct ionic_admin_ctx *ctx);
diff --git a/drivers/net/ethernet/pensando/ionic/ionic_aux.c b/drivers/net/ethernet/pensando/ionic/ionic_aux.c
index 370a7eff3e28..521f3bd9aee1 100644
--- a/drivers/net/ethernet/pensando/ionic/ionic_aux.c
+++ b/drivers/net/ethernet/pensando/ionic/ionic_aux.c
@@ -2,6 +2,8 @@
 /* Copyright (C) 2018-2025, Advanced Micro Devices, Inc. */
 
 #include <linux/kernel.h>
+#include <linux/ionic/ionic_hwmon.h>
+
 #include "ionic.h"
 #include "ionic_lif.h"
 #include "ionic_aux.h"
@@ -17,11 +19,39 @@ static bool ionic_rdma_supported(struct ionic *ionic)
 	return le64_to_cpu(ionic->ident.lif.capabilities) & IONIC_LIF_CAP_RDMA;
 }
 
+static bool ionic_hwmon_supported(struct ionic *ionic)
+{
+	return le64_to_cpu(ionic->ident.dev.capabilities) & IONIC_DEV_CAP_HWMON;
+}
+
+static int ionic_hwmon_prepare(struct ionic *ionic)
+{
+	void *buf;
+
+	if (ionic->hwmon_caps_buf)
+		return 0;
+
+	buf = dmam_alloc_coherent(ionic->dev, IONIC_HWMON_CAPS_BUF_SIZE,
+				  &ionic->hwmon_caps_pa, GFP_KERNEL);
+	if (!buf) {
+		dev_warn(ionic->dev, "Failed to allocate hwmon buffer\n");
+		return -ENOMEM;
+	}
+
+	ionic->hwmon_caps_buf = buf;
+	return 0;
+}
+
 static const struct ionic_aux_type_info ionic_aux_types[IONIC_AUX_MAX] = {
 	[IONIC_AUX_RDMA] = {
 		.name = "rdma",
 		.supported = ionic_rdma_supported,
 	},
+	[IONIC_AUX_HWMON] = {
+		.name = "hwmon",
+		.supported = ionic_hwmon_supported,
+		.prepare = ionic_hwmon_prepare,
+	},
 };
 
 static void ionic_auxbus_release(struct device *dev)
@@ -117,6 +147,85 @@ void ionic_auxbus_unregister(struct ionic_lif *lif)
 	mutex_unlock(&lif->adev_lock);
 }
 
+static struct ionic_lif *ionic_hwmon_lif(struct auxiliary_device *adev)
+{
+	return container_of(adev, struct ionic_aux_dev, adev)->lif;
+}
+
+int ionic_hwmon_get_caps(struct auxiliary_device *adev, u8 max_ver,
+			 const void **buf, size_t *len, u8 *ver)
+{
+	struct ionic_lif *lif = ionic_hwmon_lif(adev);
+	struct ionic *ionic = lif->ionic;
+	struct ionic_admin_ctx ctx = {
+		.work = COMPLETION_INITIALIZER_ONSTACK(ctx.work),
+		.comp.comp.status = IONIC_RC_EIO,
+		.cmd.hwmon_getcaps = {
+			.opcode = IONIC_CMD_HWMON_GETCAPS,
+			.ver = max_ver,
+			.lif_index = cpu_to_le16(lif->index),
+			.resp_buf_len = cpu_to_le32(IONIC_HWMON_CAPS_BUF_SIZE),
+			.resp_dma_addr = cpu_to_le64(ionic->hwmon_caps_pa),
+		},
+	};
+	int err;
+
+	if (!ionic->hwmon_caps_buf)
+		return -ENODEV;
+
+	memset(ionic->hwmon_caps_buf, 0, IONIC_HWMON_CAPS_BUF_SIZE);
+
+	err = ionic_adminq_post_wait_nomsg(lif, &ctx);
+	if (err)
+		return err;
+
+	if (ctx.comp.comp.status)
+		return ionic_error_to_errno(ctx.comp.comp.status);
+
+	*buf = ionic->hwmon_caps_buf;
+	*len = IONIC_HWMON_CAPS_BUF_SIZE;
+	*ver = ctx.comp.hwmon_getcaps.ver;
+
+	return 0;
+}
+EXPORT_SYMBOL_NS_GPL(ionic_hwmon_get_caps, "NET_IONIC");
+
+int ionic_hwmon_get_attr(struct auxiliary_device *adev, u8 type, u8 channel,
+			 u8 attr, u32 *val)
+{
+	struct ionic_lif *lif = ionic_hwmon_lif(adev);
+	struct ionic_admin_ctx ctx = {
+		.work = COMPLETION_INITIALIZER_ONSTACK(ctx.work),
+		.comp.comp.status = IONIC_RC_EIO,
+		.cmd.hwmon_getattr = {
+			.opcode = IONIC_CMD_HWMON_GETATTR,
+			.lif_index = cpu_to_le16(lif->index),
+			.sensor_type = type,
+			.channel = channel,
+			.attr = attr,
+		},
+	};
+	int err;
+
+	err = ionic_adminq_post_wait_nomsg(lif, &ctx);
+	if (err)
+		return err;
+
+	if (ctx.comp.comp.status)
+		return ionic_error_to_errno(ctx.comp.comp.status);
+
+	*val = le32_to_cpu(ctx.comp.hwmon_getattr.attr_value);
+
+	return 0;
+}
+EXPORT_SYMBOL_NS_GPL(ionic_hwmon_get_attr, "NET_IONIC");
+
+struct device *ionic_hwmon_dev(struct auxiliary_device *adev)
+{
+	return ionic_hwmon_lif(adev)->ionic->dev;
+}
+EXPORT_SYMBOL_NS_GPL(ionic_hwmon_dev, "NET_IONIC");
+
 void ionic_request_rdma_reset(struct ionic_lif *lif)
 {
 	struct ionic *ionic = lif->ionic;
diff --git a/drivers/net/ethernet/pensando/ionic/ionic_lif.h b/drivers/net/ethernet/pensando/ionic/ionic_lif.h
index d04503b19c51..95bcfcded562 100644
--- a/drivers/net/ethernet/pensando/ionic/ionic_lif.h
+++ b/drivers/net/ethernet/pensando/ionic/ionic_lif.h
@@ -182,6 +182,7 @@ struct ionic_phc;
 
 enum ionic_aux_type {
 	IONIC_AUX_RDMA,
+	IONIC_AUX_HWMON,
 	IONIC_AUX_MAX,
 };
 
diff --git a/include/linux/ionic/ionic_hwmon.h b/include/linux/ionic/ionic_hwmon.h
index 62667e3d7135..bc82f2903386 100644
--- a/include/linux/ionic/ionic_hwmon.h
+++ b/include/linux/ionic/ionic_hwmon.h
@@ -135,4 +135,44 @@ struct ionic_hwmon_caps_hdr {
 	__le16	n_channels[];
 };
 
+struct auxiliary_device;
+struct device;
+
+/**
+ * ionic_hwmon_get_caps - Read the sensor capabilities from the device
+ * @adev:    ionic "hwmon" auxiliary device
+ * @max_ver: highest capabilities buffer layout version the caller parses
+ * @buf:     set to the capabilities buffer
+ * @len:     set to the length of @buf
+ * @ver:     set to the layout version of @buf, as reported by the device
+ *
+ * The buffer belongs to ionic and is overwritten by the next call.
+ *
+ * Return: zero or negative error status
+ */
+int ionic_hwmon_get_caps(struct auxiliary_device *adev, u8 max_ver,
+			 const void **buf, size_t *len, u8 *ver);
+
+/**
+ * ionic_hwmon_get_attr - Read one sensor attribute from the device
+ * @adev:    ionic "hwmon" auxiliary device
+ * @type:    sensor type from enum ionic_hwmon_sensor_type
+ * @channel: channel index within @type
+ * @attr:    attribute ID from the attribute enum for @type
+ * @val:     set to the attribute value, in the units documented for
+ *           struct ionic_hwmon_getattr_comp
+ *
+ * Return: zero or negative error status
+ */
+int ionic_hwmon_get_attr(struct auxiliary_device *adev, u8 type, u8 channel,
+			 u8 attr, u32 *val);
+
+/**
+ * ionic_hwmon_dev - Device to parent the hwmon device to
+ * @adev: ionic "hwmon" auxiliary device
+ *
+ * Return: the PCI function's device
+ */
+struct device *ionic_hwmon_dev(struct auxiliary_device *adev);
+
 #endif /* _LINUX_IONIC_HWMON_H_ */

-- 
2.43.0