hwstub/qeditor: add support for atomic read/writes

The current code assumed that READ/WRITE would produce atomic read/writes for
8/16/32-bit words, which in turned put assumption on the memcpy function.
Since some memcpy implementation do not always guarantee such strong assumption,
introduce two new operation READ/WRITE_ATOMIC which provide the necessary
tools to do correct read and write to register in a single memory access.

Change-Id: I37451bd5057bb0dcaf5a800d8aef8791c792a090

2 files changed, 36 insertions, 9 deletions

diff --git a/utils/hwstub/lib/hwstub.c b/utils/hwstub/lib/hwstub.c
index 6ae0400a66..d3908585da 100644
--- a/utils/hwstub/lib/hwstub.c
+++ b/utils/hwstub/lib/hwstub.c
@@ -140,7 +140,8 @@ int hwstub_get_log(struct hwstub_device_t *dev, void *buf, size_t sz)
         HWSTUB_GET_LOG, 0, dev->intf, buf, sz, 1000);
 }
 
-static int _hwstub_read(struct hwstub_device_t *dev, uint32_t addr, void *buf, size_t sz)
+static int _hwstub_read(struct hwstub_device_t *dev, uint8_t breq, uint32_t addr,
+    void *buf, size_t sz)
 {
     struct hwstub_read_req_t read;
     read.dAddress = addr;
@@ -151,10 +152,11 @@ static int _hwstub_read(struct hwstub_device_t *dev, uint32_t addr, void *buf, s
         return -1;
     return libusb_control_transfer(dev->handle,
         LIBUSB_REQUEST_TYPE_CLASS | LIBUSB_RECIPIENT_INTERFACE | LIBUSB_ENDPOINT_IN,
-        HWSTUB_READ2, dev->id++, dev->intf, buf, sz, 1000);
+        breq, dev->id++, dev->intf, buf, sz, 1000);
 }
 
-static int _hwstub_write(struct hwstub_device_t *dev, uint32_t addr, void *buf, size_t sz)
+static int _hwstub_write(struct hwstub_device_t *dev, uint8_t breq, uint32_t addr,
+    const void *buf, size_t sz)
 {
     size_t hdr_sz = sizeof(struct hwstub_write_req_t);
     struct hwstub_write_req_t *req = malloc(sz + hdr_sz);
@@ -162,18 +164,34 @@ static int _hwstub_write(struct hwstub_device_t *dev, uint32_t addr, void *buf,
     memcpy(req + 1, buf, sz);
     int size = libusb_control_transfer(dev->handle,
         LIBUSB_REQUEST_TYPE_CLASS | LIBUSB_RECIPIENT_INTERFACE | LIBUSB_ENDPOINT_OUT,
-        HWSTUB_WRITE, dev->id++, dev->intf, (void *)req, sz + hdr_sz, 1000);
+        breq, dev->id++, dev->intf, (void *)req, sz + hdr_sz, 1000);
     free(req);
     return size - hdr_sz;
 }
 
+int hwstub_read_atomic(struct hwstub_device_t *dev, uint32_t addr, void *buf, size_t sz)
+{
+    /* reject any read greater than the buffer, it makes no sense anyway */
+    if(sz > dev->buf_sz)
+        return -1;
+    return _hwstub_read(dev, HWSTUB_READ2_ATOMIC, addr, buf, sz);
+}
+
+int hwstub_write_atomic(struct hwstub_device_t *dev, uint32_t addr, const void *buf, size_t sz)
+{
+    /* reject any write greater than the buffer, it makes no sense anyway */
+    if(sz + sizeof(struct hwstub_write_req_t) > dev->buf_sz)
+        return -1;
+    return _hwstub_write(dev, HWSTUB_WRITE_ATOMIC, addr, buf, sz);
+}
+
 /* Intermediate function which make sure we don't overflow the device buffer */
 int hwstub_read(struct hwstub_device_t *dev, uint32_t addr, void *buf, size_t sz)
 {
     int cnt = 0;
     while(sz > 0)
     {
-        int xfer = _hwstub_read(dev, addr, buf, MIN(sz, dev->buf_sz));
+        int xfer = _hwstub_read(dev, HWSTUB_READ2, addr, buf, MIN(sz, dev->buf_sz));
         if(xfer <  0)
             return xfer;
         sz -= xfer;
@@ -185,13 +203,13 @@ int hwstub_read(struct hwstub_device_t *dev, uint32_t addr, void *buf, size_t sz
 }
 
 /* Intermediate function which make sure we don't overflow the device buffer */
-int hwstub_write(struct hwstub_device_t *dev, uint32_t addr, void *buf, size_t sz)
+int hwstub_write(struct hwstub_device_t *dev, uint32_t addr, const void *buf, size_t sz)
 {
     int cnt = 0;
     while(sz > 0)
     {
-        int xfer = _hwstub_write(dev, addr, buf, MIN(sz, dev->buf_sz -
-            sizeof(struct hwstub_write_req_t)));
+        int xfer = _hwstub_write(dev, HWSTUB_WRITE, addr, buf, 
+            MIN(sz, dev->buf_sz - sizeof(struct hwstub_write_req_t)));
         if(xfer <  0)
             return xfer;
         sz -= xfer;
@@ -207,6 +225,12 @@ int hwstub_rw_mem(struct hwstub_device_t *dev, int read, uint32_t addr, void *bu
     return read ? hwstub_read(dev, addr, buf, sz) : hwstub_write(dev, addr, buf, sz);
 }
 
+int hwstub_rw_mem_atomic(struct hwstub_device_t *dev, int read, uint32_t addr, void *buf, size_t sz)
+{
+    return read ? hwstub_read_atomic(dev, addr, buf, sz) :
+        hwstub_write_atomic(dev, addr, buf, sz);
+}
+
 int hwstub_exec(struct hwstub_device_t *dev, uint32_t addr, uint16_t flags)
 {
     struct hwstub_exec_req_t exec;
diff --git a/utils/hwstub/lib/hwstub.h b/utils/hwstub/lib/hwstub.h
index d7d6ceb8ef..4d12de8eda 100644
--- a/utils/hwstub/lib/hwstub.h
+++ b/utils/hwstub/lib/hwstub.h
@@ -53,8 +53,11 @@ int hwstub_get_desc(struct hwstub_device_t *dev, uint16_t desc, void *info, size
 int hwstub_get_log(struct hwstub_device_t *dev, void *buf, size_t sz);
 /* Returns number of bytes written/read or <0 on error */
 int hwstub_read(struct hwstub_device_t *dev, uint32_t addr, void *buf, size_t sz);
-int hwstub_write(struct hwstub_device_t *dev, uint32_t addr, void *buf, size_t sz);
+int hwstub_read_atomic(struct hwstub_device_t *dev, uint32_t addr, void *buf, size_t sz);
+int hwstub_write(struct hwstub_device_t *dev, uint32_t addr, const void *buf, size_t sz);
+int hwstub_write_atomic(struct hwstub_device_t *dev, uint32_t addr, const void *buf, size_t sz);
 int hwstub_rw_mem(struct hwstub_device_t *dev, int read, uint32_t addr, void *buf, size_t sz);
+int hwstub_rw_mem_atomic(struct hwstub_device_t *dev, int read, uint32_t addr, void *buf, size_t sz);
 /* Returns <0 on error */
 int hwstub_exec(struct hwstub_device_t *dev, uint32_t addr, uint16_t flags);
 int hwstub_call(struct hwstub_device_t *dev, uint32_t addr);