[RFC PATCH v6 09/11] hw/ssi: imx_spi: Round up the burst length to be multiple of 8

["Philippe Mathieu-Daudé" <f4bug@amsat.org>]

From: Bin Meng <bin.meng@windriver.com>

Current implementation of the imx spi controller expects the burst
length to be multiple of 8, which is the most common use case.

In case the burst length is not what we expect, log it to give user
a chance to notice it, and round it up to be multiple of 8.

Signed-off-by: Bin Meng <bin.meng@windriver.com>
Message-Id: <20210112145526.31095-5-bmeng.cn@gmail.com>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
---
 hw/ssi/imx_spi.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/hw/ssi/imx_spi.c b/hw/ssi/imx_spi.c
index 2f9e800dd3a..638959daa08 100644
--- a/hw/ssi/imx_spi.c
+++ b/hw/ssi/imx_spi.c
@@ -129,7 +129,20 @@ static uint8_t imx_spi_selected_channel(IMXSPIState *s)
 
 static uint32_t imx_spi_burst_length(IMXSPIState *s)
 {
-    return EXTRACT(s->regs[ECSPI_CONREG], ECSPI_CONREG_BURST_LENGTH) + 1;
+    uint32_t burst;
+
+    burst = EXTRACT(s->regs[ECSPI_CONREG], ECSPI_CONREG_BURST_LENGTH) + 1;
+    if (burst % 8) {
+        qemu_log_mask(LOG_UNIMP,
+                      "[%s]%s: burst length (%d) not multiple of 8!\n",
+                      TYPE_IMX_SPI, __func__, burst);
+        burst = ROUND_UP(burst, 8);
+        qemu_log_mask(LOG_UNIMP,
+                      "[%s]%s: burst length rounded up to %d; this may not work.\n",
+                      TYPE_IMX_SPI, __func__, burst);
+    }
+
+    return burst;
 }
 
 static bool imx_spi_is_enabled(IMXSPIState *s)
-- 
2.26.2