piolib: Increase data_bytes range to 32-bits

In many places, the number of bytes in a data transfer is stored as a 32-bit (or greater) value, but the ioctl API to the kernel stores it in a 16-bit field, alongside which is a 16-bit gap due to the alignment requirements of the pointer that follows. Increase the size of data_bytes to a uint32_t, so that it can handle larger transfers. Since using different sizes as either end can lead to unpredictable results, a separate IOCTL is used for larger transfers, allowing the kernel support to be determined and backwards compatibility to be maintained. See: raspberrypi#107 Signed-off-by: Phil Elwell <[email protected]>
pelwell · Dec 16, 2024 · 3e804d4 · 3e804d4
1 parent 9d884c7
commit 3e804d4
Show file tree

Hide file tree

Showing 2 changed files with 13 additions and 5 deletions.
diff --git a/piolib/include/rp1_pio_if.h b/piolib/include/rp1_pio_if.h
@@ -167,6 +167,13 @@ struct rp1_pio_sm_xfer_data_args {
     void *data;
 };
 
+struct rp1_pio_sm_xfer_data32_args {
+    uint16_t sm;
+    uint16_t dir;
+    uint32_t data_bytes;
+    void *data;
+};
+
 struct rp1_access_hw_args {
     uint32_t addr;
     uint32_t len;
@@ -177,10 +184,7 @@ struct rp1_access_hw_args {
 
 #define PIO_IOC_SM_CONFIG_XFER _IOW(PIO_IOC_MAGIC, 0, struct rp1_pio_sm_config_xfer_args)
 #define PIO_IOC_SM_XFER_DATA _IOW(PIO_IOC_MAGIC, 1, struct rp1_pio_sm_xfer_data_args)
-
-#ifdef CONFIG_COMPAT
-//XXX #define PIO_IOC_SM_XFER_DATA32 _IOW(PIO_IOC_MAGIC, 2, struct pio_sm_xfer_data_args)
-#endif
+#define PIO_IOC_SM_XFER_DATA32 _IOW(PIO_IOC_MAGIC, 2, struct rp1_pio_sm_xfer_data32_args)
 
 #define PIO_IOC_READ_HW _IOW(PIO_IOC_MAGIC, 8, struct rp1_access_hw_args)
 #define PIO_IOC_WRITE_HW _IOW(PIO_IOC_MAGIC, 9, struct rp1_access_hw_args)

diff --git a/piolib/pio_rp1.c b/piolib/pio_rp1.c
@@ -265,9 +265,13 @@ static int rp1_pio_sm_config_xfer(PIO pio, uint sm, uint dir, uint buf_size, uin
 static int rp1_pio_sm_xfer_data(PIO pio, uint sm, uint dir, uint data_bytes, void *data)
 {
     struct rp1_pio_sm_xfer_data_args args = { .sm = sm, .dir = dir, .data_bytes = data_bytes, .data = data };
+    struct rp1_pio_sm_xfer_data32_args args32 = { .sm = sm, .dir = dir, .data_bytes = data_bytes, .data = data };
     int err;
     check_sm_param(sm);
-    err = rp1_ioctl(pio, PIO_IOC_SM_XFER_DATA, &args);
+    if (data_bytes > 0xffff)
+        err = rp1_ioctl(pio, PIO_IOC_SM_XFER_DATA32, &args32);
+    else
+        err = rp1_ioctl(pio, PIO_IOC_SM_XFER_DATA, &args);
     return (err > 0);
 }