[cip-dev] [RFC PATCH 4.19.y-cip 26/50] PCI: endpoint: Assign function number for each PF in EPC core

Lad Prabhakar
2020-10-12T14:21:00Z

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From: Kishon Vijay Abraham I <kishon@ti.com>

commit 2499ee84e02774a8573b7b4c76c8f2ea38669313 upstream.

The PCIe endpoint core relies on the drivers that invoke the
pci_epc_add_epf() API to allocate and assign a function number
to each physical function (PF). Since endpoint function device can
be created by multiple mechanisms (configfs, devicetree, etc..),
allowing each of these mechanisms to assign a function number
would result in mutliple endpoint function devices having the
same function number. In order to avoid this, let EPC core assign
a function number to the endpoint device.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
---
drivers/pci/endpoint/pci-ep-cfs.c | 27 +++++----------------------
drivers/pci/endpoint/pci-epc-core.c | 26 ++++++++++++++++++++++----
include/linux/pci-epc.h | 2 ++
3 files changed, 29 insertions(+), 26 deletions(-)

diff --git a/drivers/pci/endpoint/pci-ep-cfs.c b/drivers/pci/endpoint/pci-ep-cfs.c
index d1288a0bd530..e7e8367eead1 100644
--- a/drivers/pci/endpoint/pci-ep-cfs.c
+++ b/drivers/pci/endpoint/pci-ep-cfs.c
@@ -29,7 +29,6 @@ struct pci_epc_group {
struct config_group group;
struct pci_epc *epc;
bool start;
- unsigned long function_num_map;
};

static inline struct pci_epf_group *to_pci_epf_group(struct config_item *item)
@@ -89,37 +88,22 @@ static int pci_epc_epf_link(struct config_item *epc_item,
struct config_item *epf_item)
{
int ret;
- u32 func_no = 0;
struct pci_epf_group *epf_group = to_pci_epf_group(epf_item);
struct pci_epc_group *epc_group = to_pci_epc_group(epc_item);
struct pci_epc *epc = epc_group->epc;
struct pci_epf *epf = epf_group->epf;

- func_no = find_first_zero_bit(&epc_group->function_num_map,
- BITS_PER_LONG);
- if (func_no >= BITS_PER_LONG)
- return -EINVAL;
-
- set_bit(func_no, &epc_group->function_num_map);
- epf->func_no = func_no;
-
ret = pci_epc_add_epf(epc, epf);
if (ret)
- goto err_add_epf;
+ return ret;

ret = pci_epf_bind(epf);
- if (ret)
- goto err_epf_bind;
+ if (ret) {
+ pci_epc_remove_epf(epc, epf);
+ return ret;
+ }

return 0;
-
-err_epf_bind:
- pci_epc_remove_epf(epc, epf);
-
-err_add_epf:
- clear_bit(func_no, &epc_group->function_num_map);
-
- return ret;
}

static void pci_epc_epf_unlink(struct config_item *epc_item,
@@ -134,7 +118,6 @@ static void pci_epc_epf_unlink(struct config_item *epc_item,

epc = epc_group->epc;
epf = epf_group->epf;
- clear_bit(epf->func_no, &epc_group->function_num_map);
pci_epf_unbind(epf);
pci_epc_remove_epf(epc, epf);
}
diff --git a/drivers/pci/endpoint/pci-epc-core.c b/drivers/pci/endpoint/pci-epc-core.c
index e51a12ed85bb..dc1c673534e0 100644
--- a/drivers/pci/endpoint/pci-epc-core.c
+++ b/drivers/pci/endpoint/pci-epc-core.c
@@ -471,22 +471,39 @@ EXPORT_SYMBOL_GPL(pci_epc_write_header);
*/
int pci_epc_add_epf(struct pci_epc *epc, struct pci_epf *epf)
{
+ u32 func_no;
+ int ret = 0;
+
if (epf->epc)
return -EBUSY;

if (IS_ERR(epc))
return -EINVAL;

- if (epf->func_no > epc->max_functions - 1)
- return -EINVAL;
+ mutex_lock(&epc->lock);
+ func_no = find_first_zero_bit(&epc->function_num_map,
+ BITS_PER_LONG);
+ if (func_no >= BITS_PER_LONG) {
+ ret = -EINVAL;
+ goto ret;
+ }
+
+ if (func_no > epc->max_functions - 1) {
+ dev_err(&epc->dev, "Exceeding max supported Function Number\n");
+ ret = -EINVAL;
+ goto ret;
+ }

+ set_bit(func_no, &epc->function_num_map);
+ epf->func_no = func_no;
epf->epc = epc;

- mutex_lock(&epc->lock);
list_add_tail(&epf->list, &epc->pci_epf);
+
+ret:
mutex_unlock(&epc->lock);

- return 0;
+ return ret;
}
EXPORT_SYMBOL_GPL(pci_epc_add_epf);

@@ -503,6 +520,7 @@ void pci_epc_remove_epf(struct pci_epc *epc, struct pci_epf *epf)
return;

mutex_lock(&epc->lock);
+ clear_bit(epf->func_no, &epc->function_num_map);
list_del(&epf->list);
epf->epc = NULL;
mutex_unlock(&epc->lock);
diff --git a/include/linux/pci-epc.h b/include/linux/pci-epc.h
index 9b21692bc2e4..44bfbeb480bb 100644
--- a/include/linux/pci-epc.h
+++ b/include/linux/pci-epc.h
@@ -92,6 +92,7 @@ struct pci_epc_mem {
* @max_functions: max number of functions that can be configured in this EPC
* @group: configfs group representing the PCI EPC device
* @lock: mutex to protect pci_epc ops
+ * @function_num_map: bitmap to manage physical function number
* @notifier: used to notify EPF of any EPC events (like linkup)
*/
struct pci_epc {
@@ -103,6 +104,7 @@ struct pci_epc {
struct config_group *group;
/* mutex to protect against concurrent access of EP controller */
struct mutex lock;
+ unsigned long function_num_map;
struct atomic_notifier_head notifier;
};

--
2.17.1

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