cxl: Support to flash a new image on the adapter from a guest

The new flash.c file contains the logic to flash a new image on the
adapter, through a hcall. It is an iterative process, with chunks of
data of 1M at a time. There are also 2 phases: write and verify. The
flash operation itself is driven from a user-land tool.
Once flashing is successful, an rtas call is made to update the device
tree with the new properties values for the adapter and the AFU(s)

Add a new char device for the adapter, so that the flash tool can
access the card, even if there is no valid AFU on it.

Co-authored-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com>
Signed-off-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com>
Signed-off-by: Christophe Lombard <clombard@linux.vnet.ibm.com>
Reviewed-by: Manoj Kumar <manoj@linux.vnet.ibm.com>
Acked-by: Ian Munsie <imunsie@au1.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Documentation/powerpc/cxl.txt

@@ -116,6 +116,8 @@ Work Element Descriptor (WED)
 User API
 ========
 
+1. AFU character devices
+
     For AFUs operating in AFU directed mode, two character device
     files will be created. /dev/cxl/afu0.0m will correspond to a
     master context and /dev/cxl/afu0.0s will correspond to a slave
@@ -362,6 +364,59 @@ read
         reserved fields:
             For future extensions and padding
 
+
+2. Card character device (powerVM guest only)
+
+    In a powerVM guest, an extra character device is created for the
+    card. The device is only used to write (flash) a new image on the
+    FPGA accelerator. Once the image is written and verified, the
+    device tree is updated and the card is reset to reload the updated
+    image.
+
+open
+----
+
+    Opens the device and allocates a file descriptor to be used with
+    the rest of the API. The device can only be opened once.
+
+ioctl
+-----
+
+CXL_IOCTL_DOWNLOAD_IMAGE:
+CXL_IOCTL_VALIDATE_IMAGE:
+    Starts and controls flashing a new FPGA image. Partial
+    reconfiguration is not supported (yet), so the image must contain
+    a copy of the PSL and AFU(s). Since an image can be quite large,
+    the caller may have to iterate, splitting the image in smaller
+    chunks.
+
+    Takes a pointer to a struct cxl_adapter_image:
+        struct cxl_adapter_image {
+            __u64 flags;
+            __u64 data;
+            __u64 len_data;
+            __u64 len_image;
+            __u64 reserved1;
+            __u64 reserved2;
+            __u64 reserved3;
+            __u64 reserved4;
+        };
+
+    flags:
+        These flags indicate which optional fields are present in
+        this struct. Currently all fields are mandatory.
+
+    data:
+        Pointer to a buffer with part of the image to write to the
+        card.
+
+    len_data:
+        Size of the buffer pointed to by data.
+
+    len_image:
+        Full size of the image.
+
+
 Sysfs Class
 ===========
 

drivers/misc/cxl/Makefile

@@ -4,7 +4,7 @@ ccflags-$(CONFIG_PPC_WERROR)	+= -Werror
 cxl-y				+= main.o file.o irq.o fault.o native.o
 cxl-y				+= context.o sysfs.o debugfs.o pci.o trace.o
 cxl-y				+= vphb.o api.o
-cxl-$(CONFIG_PPC_PSERIES)	+= guest.o of.o hcalls.o
+cxl-$(CONFIG_PPC_PSERIES)	+= flash.o guest.o of.o hcalls.o
 obj-$(CONFIG_CXL)		+= cxl.o
 obj-$(CONFIG_CXL_BASE)		+= base.o
 

drivers/misc/cxl/base.c

@@ -84,3 +84,10 @@ void unregister_cxl_calls(struct cxl_calls *calls)
 	synchronize_rcu();
 }
 EXPORT_SYMBOL_GPL(unregister_cxl_calls);
+
+int cxl_update_properties(struct device_node *dn,
+			  struct property *new_prop)
+{
+	return of_update_property(dn, new_prop);
+}
+EXPORT_SYMBOL_GPL(cxl_update_properties);

drivers/misc/cxl/cxl.h

@@ -324,6 +324,10 @@ static const cxl_p2n_reg_t CXL_PSL_WED_An     = {0x0A0};
 #define CXL_MODE_TIME_SLICED 0x4
 #define CXL_SUPPORTED_MODES (CXL_MODE_DEDICATED | CXL_MODE_DIRECTED)
 
+#define CXL_DEV_MINORS 13   /* 1 control + 4 AFUs * 3 (dedicated/master/shared) */
+#define CXL_CARD_MINOR(adapter) (adapter->adapter_num * CXL_DEV_MINORS)
+#define CXL_DEVT_ADAPTER(dev) (MINOR(dev) / CXL_DEV_MINORS)
+
 enum cxl_context_status {
 	CLOSED,
 	OPENED,
@@ -692,12 +696,14 @@ struct cxl_calls {
 };
 int register_cxl_calls(struct cxl_calls *calls);
 void unregister_cxl_calls(struct cxl_calls *calls);
+int cxl_update_properties(struct device_node *dn, struct property *new_prop);
 
 void cxl_remove_adapter_nr(struct cxl *adapter);
 
 int cxl_alloc_spa(struct cxl_afu *afu);
 void cxl_release_spa(struct cxl_afu *afu);
 
+dev_t cxl_get_dev(void);
 int cxl_file_init(void);
 void cxl_file_exit(void);
 int cxl_register_adapter(struct cxl *adapter);

drivers/misc/cxl/file.c

@@ -26,17 +26,14 @@
 #include "trace.h"
 
 #define CXL_NUM_MINORS 256 /* Total to reserve */
-#define CXL_DEV_MINORS 13   /* 1 control + 4 AFUs * 3 (dedicated/master/shared) */
 
-#define CXL_CARD_MINOR(adapter) (adapter->adapter_num * CXL_DEV_MINORS)
 #define CXL_AFU_MINOR_D(afu) (CXL_CARD_MINOR(afu->adapter) + 1 + (3 * afu->slice))
 #define CXL_AFU_MINOR_M(afu) (CXL_AFU_MINOR_D(afu) + 1)
 #define CXL_AFU_MINOR_S(afu) (CXL_AFU_MINOR_D(afu) + 2)
 #define CXL_AFU_MKDEV_D(afu) MKDEV(MAJOR(cxl_dev), CXL_AFU_MINOR_D(afu))
 #define CXL_AFU_MKDEV_M(afu) MKDEV(MAJOR(cxl_dev), CXL_AFU_MINOR_M(afu))
 #define CXL_AFU_MKDEV_S(afu) MKDEV(MAJOR(cxl_dev), CXL_AFU_MINOR_S(afu))
 
-#define CXL_DEVT_ADAPTER(dev) (MINOR(dev) / CXL_DEV_MINORS)
 #define CXL_DEVT_AFU(dev) ((MINOR(dev) % CXL_DEV_MINORS - 1) / 3)
 
 #define CXL_DEVT_IS_CARD(dev) (MINOR(dev) % CXL_DEV_MINORS == 0)
@@ -446,7 +443,8 @@ static const struct file_operations afu_master_fops = {
 
 static char *cxl_devnode(struct device *dev, umode_t *mode)
 {
-	if (CXL_DEVT_IS_CARD(dev->devt)) {
+	if (cpu_has_feature(CPU_FTR_HVMODE) &&
+	    CXL_DEVT_IS_CARD(dev->devt)) {
 		/*
 		 * These minor numbers will eventually be used to program the
 		 * PSL and AFUs once we have dynamic reprogramming support
@@ -547,6 +545,11 @@ int cxl_register_adapter(struct cxl *adapter)
 	return device_register(&adapter->dev);
 }
 
+dev_t cxl_get_dev(void)
+{
+	return cxl_dev;
+}
+
 int __init cxl_file_init(void)
 {
 	int rc;