net/mlx5: Add Vendor Specific Capability access gateway

The Vendor Specific Capability (VSC) is used to activate a gateway
interfacing with the device. The gateway is used to read or write
device configurations, which are organized in different domains (spaces).
A configuration access may result in multiple actions, reads, writes.

Example usages are accessing the Crspace domain to read the crspace or
locking a device semaphore using the Semaphore domain.

The configuration access use pci_cfg_access to prevent parallel access to
the VSC space by the driver and userspace calls.
Signed-off-by: Alex Vesker <valex@mellanox.com>
Signed-off-by: Feras Daoud <ferasda@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>

drivers/net/ethernet/mellanox/mlx5/core/Makefile

@@ -15,7 +15,8 @@ mlx5_core-y :=	main.o cmd.o debugfs.o fw.o eq.o uar.o pagealloc.o \
 		health.o mcg.o cq.o alloc.o qp.o port.o mr.o pd.o \
 		transobj.o vport.o sriov.o fs_cmd.o fs_core.o \
 		fs_counters.o rl.o lag.o dev.o events.o wq.o lib/gid.o \
-		lib/devcom.o diag/fs_tracepoint.o diag/fw_tracer.o devlink.o
+		lib/devcom.o lib/pci_vsc.o diag/fs_tracepoint.o \
+		diag/fw_tracer.o devlink.o
 
 #
 # Netdev basic

drivers/net/ethernet/mellanox/mlx5/core/lib/pci_vsc.c

+// SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB
+/* Copyright (c) 2019 Mellanox Technologies */
+
+#include <linux/pci.h>
+#include "mlx5_core.h"
+#include "pci_vsc.h"
+
+#define MLX5_EXTRACT_C(source, offset, size)	\
+	((((u32)(source)) >> (offset)) & MLX5_ONES32(size))
+#define MLX5_EXTRACT(src, start, len)		\
+	(((len) == 32) ? (src) : MLX5_EXTRACT_C(src, start, len))
+#define MLX5_ONES32(size)			\
+	((size) ? (0xffffffff >> (32 - (size))) : 0)
+#define MLX5_MASK32(offset, size)		\
+	(MLX5_ONES32(size) << (offset))
+#define MLX5_MERGE_C(rsrc1, rsrc2, start, len)  \
+	((((rsrc2) << (start)) & (MLX5_MASK32((start), (len)))) | \
+	((rsrc1) & (~MLX5_MASK32((start), (len)))))
+#define MLX5_MERGE(rsrc1, rsrc2, start, len)	\
+	(((len) == 32) ? (rsrc2) : MLX5_MERGE_C(rsrc1, rsrc2, start, len))
+#define vsc_read(dev, offset, val) \
+	pci_read_config_dword((dev)->pdev, (dev)->vsc_addr + (offset), (val))
+#define vsc_write(dev, offset, val) \
+	pci_write_config_dword((dev)->pdev, (dev)->vsc_addr + (offset), (val))
+#define VSC_MAX_RETRIES 2048
+
+enum mlx5_vsc_state {
+	MLX5_VSC_UNLOCK,
+	MLX5_VSC_LOCK,
+};
+
+enum {
+	VSC_CTRL_OFFSET = 0x4,
+	VSC_COUNTER_OFFSET = 0x8,
+	VSC_SEMAPHORE_OFFSET = 0xc,
+	VSC_ADDR_OFFSET = 0x10,
+	VSC_DATA_OFFSET = 0x14,
+
+	VSC_FLAG_BIT_OFFS = 31,
+	VSC_FLAG_BIT_LEN = 1,
+
+	VSC_SYND_BIT_OFFS = 30,
+	VSC_SYND_BIT_LEN = 1,
+
+	VSC_ADDR_BIT_OFFS = 0,
+	VSC_ADDR_BIT_LEN = 30,
+
+	VSC_SPACE_BIT_OFFS = 0,
+	VSC_SPACE_BIT_LEN = 16,
+
+	VSC_SIZE_VLD_BIT_OFFS = 28,
+	VSC_SIZE_VLD_BIT_LEN = 1,
+
+	VSC_STATUS_BIT_OFFS = 29,
+	VSC_STATUS_BIT_LEN = 3,
+};
+
+void mlx5_pci_vsc_init(struct mlx5_core_dev *dev)
+{
+	if (!mlx5_core_is_pf(dev))
+		return;
+
+	dev->vsc_addr = pci_find_capability(dev->pdev,
+					    PCI_CAP_ID_VNDR);
+	if (!dev->vsc_addr)
+		mlx5_core_warn(dev, "Failed to get valid vendor specific ID\n");
+}
+
+int mlx5_vsc_gw_lock(struct mlx5_core_dev *dev)
+{
+	u32 counter = 0;
+	int retries = 0;
+	u32 lock_val;
+	int ret;
+
+	pci_cfg_access_lock(dev->pdev);
+	do {
+		if (retries > VSC_MAX_RETRIES) {
+			ret = -EBUSY;
+			goto pci_unlock;
+		}
+
+		/* Check if semaphore is already locked */
+		ret = vsc_read(dev, VSC_SEMAPHORE_OFFSET, &lock_val);
+		if (ret)
+			goto pci_unlock;
+
+		if (lock_val) {
+			retries++;
+			usleep_range(1000, 2000);
+			continue;
+		}
+
+		/* Read and write counter value, if written value is
+		 * the same, semaphore was acquired successfully.
+		 */
+		ret = vsc_read(dev, VSC_COUNTER_OFFSET, &counter);
+		if (ret)
+			goto pci_unlock;
+
+		ret = vsc_write(dev, VSC_SEMAPHORE_OFFSET, counter);
+		if (ret)
+			goto pci_unlock;
+
+		ret = vsc_read(dev, VSC_SEMAPHORE_OFFSET, &lock_val);
+		if (ret)
+			goto pci_unlock;
+
+		retries++;
+	} while (counter != lock_val);
+
+	return 0;
+
+pci_unlock:
+	pci_cfg_access_unlock(dev->pdev);
+	return ret;
+}
+
+int mlx5_vsc_gw_unlock(struct mlx5_core_dev *dev)
+{
+	int ret;
+
+	ret = vsc_write(dev, VSC_SEMAPHORE_OFFSET, MLX5_VSC_UNLOCK);
+	pci_cfg_access_unlock(dev->pdev);
+	return ret;
+}
+
+int mlx5_vsc_gw_set_space(struct mlx5_core_dev *dev, u16 space,
+			  u32 *ret_space_size)
+{
+	int ret;
+	u32 val = 0;
+
+	if (!mlx5_vsc_accessible(dev))
+		return -EINVAL;
+
+	if (ret_space_size)
+		*ret_space_size = 0;
+
+	/* Get a unique val */
+	ret = vsc_read(dev, VSC_CTRL_OFFSET, &val);
+	if (ret)
+		goto out;
+
+	/* Try to modify the lock */
+	val = MLX5_MERGE(val, space, VSC_SPACE_BIT_OFFS, VSC_SPACE_BIT_LEN);
+	ret = vsc_write(dev, VSC_CTRL_OFFSET, val);
+	if (ret)
+		goto out;
+
+	/* Verify lock was modified */
+	ret = vsc_read(dev, VSC_CTRL_OFFSET, &val);
+	if (ret)
+		goto out;
+
+	if (MLX5_EXTRACT(val, VSC_STATUS_BIT_OFFS, VSC_STATUS_BIT_LEN) == 0)
+		return -EINVAL;
+
+	/* Get space max address if indicated by size valid bit */
+	if (ret_space_size &&
+	    MLX5_EXTRACT(val, VSC_SIZE_VLD_BIT_OFFS, VSC_SIZE_VLD_BIT_LEN)) {
+		ret = vsc_read(dev, VSC_ADDR_OFFSET, &val);
+		if (ret) {
+			mlx5_core_warn(dev, "Failed to get max space size\n");
+			goto out;
+		}
+		*ret_space_size = MLX5_EXTRACT(val, VSC_ADDR_BIT_OFFS,
+					       VSC_ADDR_BIT_LEN);
+	}
+	return 0;
+
+out:
+	return ret;
+}
+
+static int mlx5_vsc_wait_on_flag(struct mlx5_core_dev *dev, u8 expected_val)
+{
+	int retries = 0;
+	u32 flag;
+	int ret;
+
+	do {
+		if (retries > VSC_MAX_RETRIES)
+			return -EBUSY;
+
+		ret = vsc_read(dev, VSC_ADDR_OFFSET, &flag);
+		if (ret)
+			return ret;
+		flag = MLX5_EXTRACT(flag, VSC_FLAG_BIT_OFFS, VSC_FLAG_BIT_LEN);
+		retries++;
+
+		if ((retries & 0xf) == 0)
+			usleep_range(1000, 2000);
+
+	} while (flag != expected_val);
+
+	return 0;
+}
+
+static int mlx5_vsc_gw_write(struct mlx5_core_dev *dev, unsigned int address,
+			     u32 data)
+{
+	int ret;
+
+	if (MLX5_EXTRACT(address, VSC_SYND_BIT_OFFS,
+			 VSC_FLAG_BIT_LEN + VSC_SYND_BIT_LEN))
+		return -EINVAL;
+
+	/* Set flag to 0x1 */
+	address = MLX5_MERGE(address, 1, VSC_FLAG_BIT_OFFS, 1);
+	ret = vsc_write(dev, VSC_DATA_OFFSET, data);
+	if (ret)
+		goto out;
+
+	ret = vsc_write(dev, VSC_ADDR_OFFSET, address);
+	if (ret)
+		goto out;
+
+	/* Wait for the flag to be cleared */
+	ret = mlx5_vsc_wait_on_flag(dev, 0);
+
+out:
+	return ret;
+}
+
+static int mlx5_vsc_gw_read(struct mlx5_core_dev *dev, unsigned int address,
+			    u32 *data)
+{
+	int ret;
+
+	if (MLX5_EXTRACT(address, VSC_SYND_BIT_OFFS,
+			 VSC_FLAG_BIT_LEN + VSC_SYND_BIT_LEN))
+		return -EINVAL;
+
+	ret = vsc_write(dev, VSC_ADDR_OFFSET, address);
+	if (ret)
+		goto out;
+
+	ret = mlx5_vsc_wait_on_flag(dev, 1);
+	if (ret)
+		goto out;
+
+	ret = vsc_read(dev, VSC_DATA_OFFSET, data);
+out:
+	return ret;
+}
+
+static int mlx5_vsc_gw_read_fast(struct mlx5_core_dev *dev,
+				 unsigned int read_addr,
+				 unsigned int *next_read_addr,
+				 u32 *data)
+{
+	int ret;
+
+	ret = mlx5_vsc_gw_read(dev, read_addr, data);
+	if (ret)
+		goto out;
+
+	ret = vsc_read(dev, VSC_ADDR_OFFSET, next_read_addr);
+	if (ret)
+		goto out;
+
+	*next_read_addr = MLX5_EXTRACT(*next_read_addr, VSC_ADDR_BIT_OFFS,
+				       VSC_ADDR_BIT_LEN);
+
+	if (*next_read_addr <= read_addr)
+		ret = -EINVAL;
+out:
+	return ret;
+}
+
+int mlx5_vsc_gw_read_block_fast(struct mlx5_core_dev *dev, u32 *data,
+				int length)
+{
+	unsigned int next_read_addr = 0;
+	unsigned int read_addr = 0;
+
+	while (read_addr < length) {
+		if (mlx5_vsc_gw_read_fast(dev, read_addr, &next_read_addr,
+					  &data[(read_addr >> 2)]))
+			return read_addr;
+
+		read_addr = next_read_addr;
+	}
+	return length;
+}

drivers/net/ethernet/mellanox/mlx5/core/lib/pci_vsc.h

+/* SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB */
+/* Copyright (c) 2019 Mellanox Technologies */
+
+#ifndef __MLX5_PCI_VSC_H__
+#define __MLX5_PCI_VSC_H__
+
+enum {
+	MLX5_VSC_SPACE_SCAN_CRSPACE = 0x7,
+};
+
+void mlx5_pci_vsc_init(struct mlx5_core_dev *dev);
+int mlx5_vsc_gw_lock(struct mlx5_core_dev *dev);
+int mlx5_vsc_gw_unlock(struct mlx5_core_dev *dev);
+int mlx5_vsc_gw_set_space(struct mlx5_core_dev *dev, u16 space,
+			  u32 *ret_space_size);
+int mlx5_vsc_gw_read_block_fast(struct mlx5_core_dev *dev, u32 *data,
+				int length);
+
+static inline bool mlx5_vsc_accessible(struct mlx5_core_dev *dev)
+{
+	return !!dev->vsc_addr;
+}
+
+#endif /* __MLX5_PCI_VSC_H__ */

drivers/net/ethernet/mellanox/mlx5/core/main.c

@@ -66,6 +66,7 @@
 #include "lib/vxlan.h"
 #include "lib/geneve.h"
 #include "lib/devcom.h"
+#include "lib/pci_vsc.h"
 #include "diag/fw_tracer.h"
 #include "ecpf.h"
 
@@ -763,6 +764,8 @@ static int mlx5_pci_init(struct mlx5_core_dev *dev, struct pci_dev *pdev,
 		goto err_clr_master;
 	}
 
+	mlx5_pci_vsc_init(dev);
+
 	return 0;
 
 err_clr_master:

include/linux/mlx5/driver.h

@@ -693,6 +693,7 @@ struct mlx5_core_dev {
 	struct mlx5_clock        clock;
 	struct mlx5_ib_clock_info  *clock_info;
 	struct mlx5_fw_tracer   *tracer;
+	u32                      vsc_addr;
 };
 
 struct mlx5_db {