Introduce new mwN_offset configfs attributes to specify memory window
offsets. This enables mapping multiple windows into a single BAR at
arbitrary offsets, improving layout flexibility.

Extend the control register region and add a 32-bit config version
field. Reuse the unused NTB_EPF_TOPOLOGY offset (0x0C) for a version
field. The endpoint function driver writes 1 (NTB_EPF_CTRL_VERSION_V1),
and ntb_hw_epf reads it at probe time and refuses to bind to unknown
versions.

Compatibility matrix:

            | EP v1 | EP legacy
  ----------+-------+----------
  RC v1     | v1    | legacy
  RC legacy | ? (*) | legacy

(*) An unpatched (legacy) RC may misinterpret the paired EP's intention
    and program MW layout incorrectly when offsets are used.

Signed-off-by: Koichiro Den <[email protected]>
---
 drivers/ntb/hw/epf/ntb_hw_epf.c               |  60 +++++++-
 drivers/pci/endpoint/functions/pci-epf-vntb.c | 136 ++++++++++++++++--
 2 files changed, 176 insertions(+), 20 deletions(-)

diff --git a/drivers/ntb/hw/epf/ntb_hw_epf.c b/drivers/ntb/hw/epf/ntb_hw_epf.c
index 9935da48a52e..4b3fa996219a 100644
--- a/drivers/ntb/hw/epf/ntb_hw_epf.c
+++ b/drivers/ntb/hw/epf/ntb_hw_epf.c
@@ -30,18 +30,27 @@
 #define NTB_EPF_LINK_STATUS    0x0A
 #define LINK_STATUS_UP         BIT(0)
 
-#define NTB_EPF_TOPOLOGY       0x0C
+/*
+ * Legacy unused NTB_EPF_TOPOLOGY (0x0c) is repurposed as a control version
+ * field
+ */
+#define NTB_EPF_CTRL_VERSION   0x0C
 #define NTB_EPF_LOWER_ADDR     0x10
 #define NTB_EPF_UPPER_ADDR     0x14
 #define NTB_EPF_LOWER_SIZE     0x18
 #define NTB_EPF_UPPER_SIZE     0x1C
 #define NTB_EPF_MW_COUNT       0x20
-#define NTB_EPF_MW1_OFFSET     0x24
+#define NTB_EPF_MW1_OFFSET     0x24 /* used by legacy (version=0) only */
 #define NTB_EPF_SPAD_OFFSET    0x28
 #define NTB_EPF_SPAD_COUNT     0x2C
 #define NTB_EPF_DB_ENTRY_SIZE  0x30
 #define NTB_EPF_DB_DATA(n)     (0x34 + (n) * 4)
 #define NTB_EPF_DB_OFFSET(n)   (0xB4 + (n) * 4)
+#define NTB_EPF_MW_OFFSET(n)   (0x134 + (n) * 4)
+#define NTB_EPF_MW_SIZE(n)     (0x144 + (n) * 4)
+
+#define NTB_EPF_CTRL_VERSION_LEGACY    0
+#define NTB_EPF_CTRL_VERSION_V1                1
 
 #define NTB_EPF_MIN_DB_COUNT   3
 #define NTB_EPF_MAX_DB_COUNT   31
@@ -451,11 +460,22 @@ static int ntb_epf_peer_mw_get_addr(struct ntb_dev *ntb, 
int idx,
                                    phys_addr_t *base, resource_size_t *size)
 {
        struct ntb_epf_dev *ndev = ntb_ndev(ntb);
-       u32 offset = 0;
+       resource_size_t bar_sz;
+       u32 offset, sz, ver;
        int bar;
 
-       if (idx == 0)
-               offset = readl(ndev->ctrl_reg + NTB_EPF_MW1_OFFSET);
+       ver = readl(ndev->ctrl_reg + NTB_EPF_CTRL_VERSION);
+       if (ver == NTB_EPF_CTRL_VERSION_LEGACY) {
+               /* Legacy layout: only MW1 offset exists, and there is no 
MW_SIZE[] */
+               if (idx == 0)
+                       offset = readl(ndev->ctrl_reg + NTB_EPF_MW1_OFFSET);
+               else
+                       offset = 0;
+               sz = 0;
+       } else {
+               offset = readl(ndev->ctrl_reg + NTB_EPF_MW_OFFSET(idx));
+               sz = readl(ndev->ctrl_reg + NTB_EPF_MW_SIZE(idx));
+       }
 
        bar = ntb_epf_mw_to_bar(ndev, idx);
        if (bar < 0)
@@ -464,8 +484,11 @@ static int ntb_epf_peer_mw_get_addr(struct ntb_dev *ntb, 
int idx,
        if (base)
                *base = pci_resource_start(ndev->ntb.pdev, bar) + offset;
 
-       if (size)
-               *size = pci_resource_len(ndev->ntb.pdev, bar) - offset;
+       if (size) {
+               bar_sz = pci_resource_len(ndev->ntb.pdev, bar);
+               *size = sz ? min_t(resource_size_t, sz, bar_sz - offset)
+                          : (bar_sz > offset ? bar_sz - offset : 0);
+       }
 
        return 0;
 }
@@ -547,6 +570,25 @@ static inline void ntb_epf_init_struct(struct ntb_epf_dev 
*ndev,
        ndev->ntb.ops = &ntb_epf_ops;
 }
 
+static int ntb_epf_check_version(struct ntb_epf_dev *ndev)
+{
+       struct device *dev = ndev->dev;
+       u32 ver;
+
+       ver = readl(ndev->ctrl_reg + NTB_EPF_CTRL_VERSION);
+
+       switch (ver) {
+       case NTB_EPF_CTRL_VERSION_LEGACY:
+       case NTB_EPF_CTRL_VERSION_V1:
+               break;
+       default:
+               dev_err(dev, "Unsupported NTB EPF version %u\n", ver);
+               return -EINVAL;
+       }
+
+       return 0;
+}
+
 static int ntb_epf_init_dev(struct ntb_epf_dev *ndev)
 {
        struct device *dev = ndev->dev;
@@ -696,6 +738,10 @@ static int ntb_epf_pci_probe(struct pci_dev *pdev,
                return ret;
        }
 
+       ret = ntb_epf_check_version(ndev);
+       if (ret)
+               return ret;
+
        ret = ntb_epf_init_dev(ndev);
        if (ret) {
                dev_err(dev, "Failed to init device\n");
diff --git a/drivers/pci/endpoint/functions/pci-epf-vntb.c 
b/drivers/pci/endpoint/functions/pci-epf-vntb.c
index c08d349db350..4927faa28255 100644
--- a/drivers/pci/endpoint/functions/pci-epf-vntb.c
+++ b/drivers/pci/endpoint/functions/pci-epf-vntb.c
@@ -39,6 +39,7 @@
 #include <linux/atomic.h>
 #include <linux/delay.h>
 #include <linux/io.h>
+#include <linux/log2.h>
 #include <linux/module.h>
 #include <linux/slab.h>
 
@@ -61,6 +62,7 @@ static struct workqueue_struct *kpcintb_workqueue;
 
 #define LINK_STATUS_UP                 BIT(0)
 
+#define CTRL_VERSION                   1
 #define SPAD_COUNT                     64
 #define DB_COUNT                       4
 #define NTB_MW_OFFSET                  2
@@ -107,7 +109,7 @@ struct epf_ntb_ctrl {
        u32 argument;
        u16 command_status;
        u16 link_status;
-       u32 topology;
+       u32 version;
        u64 addr;
        u64 size;
        u32 num_mws;
@@ -117,6 +119,8 @@ struct epf_ntb_ctrl {
        u32 db_entry_size;
        u32 db_data[MAX_DB_COUNT];
        u32 db_offset[MAX_DB_COUNT];
+       u32 mw_offset[MAX_MW];
+       u32 mw_size[MAX_MW];
 } __packed;
 
 struct epf_ntb {
@@ -128,6 +132,7 @@ struct epf_ntb {
        u32 db_count;
        u32 spad_count;
        u64 mws_size[MAX_MW];
+       u64 mws_offset[MAX_MW];
        atomic64_t db;
        u32 vbus_number;
        u16 vntb_pid;
@@ -460,10 +465,13 @@ static int epf_ntb_config_spad_bar_alloc(struct epf_ntb 
*ntb)
        ntb->reg = base;
 
        ctrl = ntb->reg;
+       ctrl->version = CTRL_VERSION;
        ctrl->spad_offset = ctrl_size;
 
        ctrl->spad_count = spad_count;
        ctrl->num_mws = ntb->num_mws;
+       memset(ctrl->mw_offset, 0, sizeof(ctrl->mw_offset));
+       memset(ctrl->mw_size, 0, sizeof(ctrl->mw_size));
        ntb->spad_size = spad_size;
 
        ctrl->db_entry_size = sizeof(u32);
@@ -695,15 +703,31 @@ static void epf_ntb_db_bar_clear(struct epf_ntb *ntb)
  */
 static int epf_ntb_mw_bar_init(struct epf_ntb *ntb)
 {
+       struct device *dev = &ntb->epf->dev;
+       u64 bar_ends[BAR_5 + 1] = { 0 };
+       unsigned long bars_used = 0;
+       enum pci_barno barno;
+       u64 off, size, end;
        int ret = 0;
        int i;
-       u64 size;
-       enum pci_barno barno;
-       struct device *dev = &ntb->epf->dev;
 
        for (i = 0; i < ntb->num_mws; i++) {
-               size = ntb->mws_size[i];
                barno = ntb->epf_ntb_bar[BAR_MW1 + i];
+               off = ntb->mws_offset[i];
+               size = ntb->mws_size[i];
+               end = off + size;
+               if (end > bar_ends[barno])
+                       bar_ends[barno] = end;
+               bars_used |= BIT(barno);
+       }
+
+       for (barno = BAR_0; barno <= BAR_5; barno++) {
+               if (!(bars_used & BIT(barno)))
+                       continue;
+               if (bar_ends[barno] < SZ_4K)
+                       size = SZ_4K;
+               else
+                       size = roundup_pow_of_two(bar_ends[barno]);
 
                ntb->epf->bar[barno].barno = barno;
                ntb->epf->bar[barno].size = size;
@@ -719,8 +743,12 @@ static int epf_ntb_mw_bar_init(struct epf_ntb *ntb)
                                      &ntb->epf->bar[barno]);
                if (ret) {
                        dev_err(dev, "MW set failed\n");
-                       goto err_alloc_mem;
+                       goto err_set_bar;
                }
+       }
+
+       for (i = 0; i < ntb->num_mws; i++) {
+               size = ntb->mws_size[i];
 
                /* Allocate EPC outbound memory windows to vpci vntb device */
                ntb->vpci_mw_addr[i] = pci_epc_mem_alloc_addr(ntb->epf->epc,
@@ -729,19 +757,31 @@ static int epf_ntb_mw_bar_init(struct epf_ntb *ntb)
                if (!ntb->vpci_mw_addr[i]) {
                        ret = -ENOMEM;
                        dev_err(dev, "Failed to allocate source address\n");
-                       goto err_set_bar;
+                       goto err_alloc_mem;
                }
        }
 
+       for (i = 0; i < ntb->num_mws; i++) {
+               ntb->reg->mw_offset[i] = (u32)ntb->mws_offset[i];
+               ntb->reg->mw_size[i] = (u32)ntb->mws_size[i];
+       }
+
        return ret;
 
-err_set_bar:
-       pci_epc_clear_bar(ntb->epf->epc,
-                         ntb->epf->func_no,
-                         ntb->epf->vfunc_no,
-                         &ntb->epf->bar[barno]);
 err_alloc_mem:
-       epf_ntb_mw_bar_clear(ntb, i);
+       while (--i >= 0)
+               pci_epc_mem_free_addr(ntb->epf->epc,
+                                     ntb->vpci_mw_phy[i],
+                                     ntb->vpci_mw_addr[i],
+                                     ntb->mws_size[i]);
+err_set_bar:
+       while (--barno >= BAR_0)
+               if (bars_used & BIT(barno))
+                       pci_epc_clear_bar(ntb->epf->epc,
+                                         ntb->epf->func_no,
+                                         ntb->epf->vfunc_no,
+                                         &ntb->epf->bar[barno]);
+
        return ret;
 }
 
@@ -1034,6 +1074,60 @@ static ssize_t epf_ntb_##_name##_store(struct 
config_item *item, \
        return len;                                                     \
 }
 
+#define EPF_NTB_MW_OFF_R(_name)                                                
\
+static ssize_t epf_ntb_##_name##_show(struct config_item *item,                
\
+                                     char *page)                       \
+{                                                                      \
+       struct config_group *group = to_config_group(item);             \
+       struct epf_ntb *ntb = to_epf_ntb(group);                        \
+       struct device *dev = &ntb->epf->dev;                            \
+       int win_no, idx;                                                \
+                                                                       \
+       if (sscanf(#_name, "mw%d_offset", &win_no) != 1)                \
+               return -EINVAL;                                         \
+                                                                       \
+       idx = win_no - 1;                                               \
+       if (idx < 0 || idx >= ntb->num_mws) {                           \
+               dev_err(dev, "MW%d out of range (num_mws=%d)\n",        \
+                       win_no, ntb->num_mws);                          \
+               return -EINVAL;                                         \
+       }                                                               \
+                                                                       \
+       idx = array_index_nospec(idx, ntb->num_mws);                    \
+       return sprintf(page, "%llu\n", ntb->mws_offset[idx]);           \
+}
+
+#define EPF_NTB_MW_OFF_W(_name)                                                
\
+static ssize_t epf_ntb_##_name##_store(struct config_item *item,       \
+                                      const char *page, size_t len)    \
+{                                                                      \
+       struct config_group *group = to_config_group(item);             \
+       struct epf_ntb *ntb = to_epf_ntb(group);                        \
+       struct device *dev = &ntb->epf->dev;                            \
+       int win_no, idx;                                                \
+       u64 val;                                                        \
+       int ret;                                                        \
+                                                                       \
+       ret = kstrtou64(page, 0, &val);                                 \
+       if (ret)                                                        \
+               return ret;                                             \
+                                                                       \
+       if (sscanf(#_name, "mw%d_offset", &win_no) != 1)                \
+               return -EINVAL;                                         \
+                                                                       \
+       idx = win_no - 1;                                               \
+       if (idx < 0 || idx >= ntb->num_mws) {                           \
+               dev_err(dev, "MW%d out of range (num_mws=%d)\n",        \
+                       win_no, ntb->num_mws);                          \
+               return -EINVAL;                                         \
+       }                                                               \
+                                                                       \
+       idx = array_index_nospec(idx, ntb->num_mws);                    \
+       ntb->mws_offset[idx] = val;                                     \
+                                                                       \
+       return len;                                                     \
+}
+
 #define EPF_NTB_BAR_R(_name, _id)                                      \
        static ssize_t epf_ntb_##_name##_show(struct config_item *item, \
                                              char *page)               \
@@ -1104,6 +1198,14 @@ EPF_NTB_MW_R(mw3)
 EPF_NTB_MW_W(mw3)
 EPF_NTB_MW_R(mw4)
 EPF_NTB_MW_W(mw4)
+EPF_NTB_MW_OFF_R(mw1_offset)
+EPF_NTB_MW_OFF_W(mw1_offset)
+EPF_NTB_MW_OFF_R(mw2_offset)
+EPF_NTB_MW_OFF_W(mw2_offset)
+EPF_NTB_MW_OFF_R(mw3_offset)
+EPF_NTB_MW_OFF_W(mw3_offset)
+EPF_NTB_MW_OFF_R(mw4_offset)
+EPF_NTB_MW_OFF_W(mw4_offset)
 EPF_NTB_BAR_R(ctrl_bar, BAR_CONFIG)
 EPF_NTB_BAR_W(ctrl_bar, BAR_CONFIG)
 EPF_NTB_BAR_R(db_bar, BAR_DB)
@@ -1124,6 +1226,10 @@ CONFIGFS_ATTR(epf_ntb_, mw1);
 CONFIGFS_ATTR(epf_ntb_, mw2);
 CONFIGFS_ATTR(epf_ntb_, mw3);
 CONFIGFS_ATTR(epf_ntb_, mw4);
+CONFIGFS_ATTR(epf_ntb_, mw1_offset);
+CONFIGFS_ATTR(epf_ntb_, mw2_offset);
+CONFIGFS_ATTR(epf_ntb_, mw3_offset);
+CONFIGFS_ATTR(epf_ntb_, mw4_offset);
 CONFIGFS_ATTR(epf_ntb_, vbus_number);
 CONFIGFS_ATTR(epf_ntb_, vntb_pid);
 CONFIGFS_ATTR(epf_ntb_, vntb_vid);
@@ -1142,6 +1248,10 @@ static struct configfs_attribute *epf_ntb_attrs[] = {
        &epf_ntb_attr_mw2,
        &epf_ntb_attr_mw3,
        &epf_ntb_attr_mw4,
+       &epf_ntb_attr_mw1_offset,
+       &epf_ntb_attr_mw2_offset,
+       &epf_ntb_attr_mw3_offset,
+       &epf_ntb_attr_mw4_offset,
        &epf_ntb_attr_vbus_number,
        &epf_ntb_attr_vntb_pid,
        &epf_ntb_attr_vntb_vid,
-- 
2.51.0


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