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[v3,03/17] firmware: turris-mox-rwtm: Use macro constant instead of hardcoded 4096

Message ID 20240617144532.17385-4-kabel@kernel.org (mailing list archive)
State Superseded
Delegated to: Arnd Bergmann
Headers show
Series Updates for turris-mox-rwtm driver | expand

Commit Message

Marek BehĂșn June 17, 2024, 2:45 p.m. UTC
The 4096 bytes limit in mox_hwrng_read() is due to the DMA buffer being
allocated to one PAGE_SIZE bytes. Use new local macro constant
RWTM_DMA_BUFFER_SIZE at allocation time and when used in mox_hwrng_read().

Use SZ_4K instead of PAGE_SIZE. Although PAGE_SIZE is never set to a
larger value on Armada 3720, it theoretically could, and this would be a
waste of space.

Signed-off-by: Marek BehĂșn <kabel@kernel.org>
 drivers/firmware/turris-mox-rwtm.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)
diff mbox series


diff --git a/drivers/firmware/turris-mox-rwtm.c b/drivers/firmware/turris-mox-rwtm.c
index 3f4758e03c81..aafd747543f6 100644
--- a/drivers/firmware/turris-mox-rwtm.c
+++ b/drivers/firmware/turris-mox-rwtm.c
@@ -11,14 +11,18 @@ 
 #include <linux/dma-mapping.h>
 #include <linux/hw_random.h>
 #include <linux/mailbox_client.h>
+#include <linux/minmax.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/of.h>
 #include <linux/platform_device.h>
+#include <linux/sizes.h>
 #include <linux/slab.h>
 #define DRIVER_NAME		"turris-mox-rwtm"
  * The macros and constants below come from Turris Mox's rWTM firmware code.
  * This firmware is open source and it's sources can be found at
@@ -287,8 +291,7 @@  static int mox_hwrng_read(struct hwrng *rng, void *data, size_t max, bool wait)
 	struct armada_37xx_rwtm_tx_msg msg;
 	int ret;
-	if (max > 4096)
-		max = 4096;
+	max = min(max, RWTM_DMA_BUFFER_SIZE);
 	msg.command = MBOX_CMD_GET_RANDOM;
 	msg.args[0] = 1;
@@ -479,8 +482,8 @@  static int turris_mox_rwtm_probe(struct platform_device *pdev)
 		return -ENOMEM;
 	rwtm->dev = dev;
-	rwtm->buf = dmam_alloc_coherent(dev, PAGE_SIZE, &rwtm->buf_phys,
-					GFP_KERNEL);
+	rwtm->buf = dmam_alloc_coherent(dev, RWTM_DMA_BUFFER_SIZE,
+					&rwtm->buf_phys, GFP_KERNEL);
 	if (!rwtm->buf)
 		return -ENOMEM;