[U-Boot] [PATCH v2 02/04] spi, spi_mxc: do not hang in spi_xchg_single

[Heiko Schocher]

if status register do never set MXC_CSPICTRL_TC, spi_xchg_single
endless loops. Add a timeout here to prevent endless hang.

Signed-off-by: Heiko Schocher <h...@denx.de>
Cc: Dirk Behme <dirk.be...@gmail.com>
Cc: Jagannadha Sutradharudu Teki <jagannadh.t...@gmail.com>

---
- changes for v2:
  - use timer api to poll till TC bit is set as Jagan Teki suggested
    and make this timeout configurable through CONFIG_SYS_SPI_MXC_WAIT
---
 README                |  4 ++++
 drivers/spi/mxc_spi.c | 18 ++++++++++++++++--
 2 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/README b/README
index a280435..ff8928b 100644
--- a/README
+++ b/README
@@ -2564,6 +2564,10 @@ CBFS (Coreboot Filesystem) support
                Enables the driver for the SPI controllers on i.MX and MXC
                SoCs. Currently i.MX31/35/51 are supported.
 
+               CONFIG_SYS_SPI_MXC_WAIT
+               Timeout for waiting until spi transfer completed.
+               default: (CONFIG_SYS_HZ/100)     /* 10 ms */
+
 - FPGA Support: CONFIG_FPGA
 
                Enables FPGA subsystem.
diff --git a/drivers/spi/mxc_spi.c b/drivers/spi/mxc_spi.c
index f3f029d..4732850 100644
--- a/drivers/spi/mxc_spi.c
+++ b/drivers/spi/mxc_spi.c
@@ -30,6 +30,10 @@ static unsigned long spi_bases[] = {
 #define reg_read readl
 #define reg_write(a, v) writel(v, a)
 
+#if !defined(CONFIG_SYS_SPI_MXC_WAIT)
+#define CONFIG_SYS_SPI_MXC_WAIT                (CONFIG_SYS_HZ/100)     /* 10 
ms */
+#endif
+
 struct mxc_spi_slave {
        struct spi_slave slave;
        unsigned long   base;
@@ -212,6 +216,8 @@ int spi_xchg_single(struct spi_slave *slave, unsigned int 
bitlen,
        int nbytes = DIV_ROUND_UP(bitlen, 8);
        u32 data, cnt, i;
        struct cspi_regs *regs = (struct cspi_regs *)mxcs->base;
+       u32 ts;
+       int status;
 
        debug("%s: bitlen %d dout 0x%x din 0x%x\n",
                __func__, bitlen, (u32)dout, (u32)din);
@@ -272,9 +278,17 @@ int spi_xchg_single(struct spi_slave *slave, unsigned int 
bitlen,
        reg_write(&regs->ctrl, mxcs->ctrl_reg |
                MXC_CSPICTRL_EN | MXC_CSPICTRL_XCH);
 
+       ts = get_timer(0);
+       status = reg_read(&regs->stat);
        /* Wait until the TC (Transfer completed) bit is set */
-       while ((reg_read(&regs->stat) & MXC_CSPICTRL_TC) == 0)
-               ;
+       while ((status & MXC_CSPICTRL_TC) == 0) {
+               if (get_timer(ts) > CONFIG_SYS_SPI_MXC_WAIT) {
+                       printf("spi_xchg_single: Timeout!\n");
+                       return -1;
+               }
+               udelay(10);
+               status = reg_read(&regs->stat);
+       }
 
        /* Transfer completed, clear any pending request */
        reg_write(&regs->stat, MXC_CSPICTRL_TC | MXC_CSPICTRL_RXOVF);
-- 
1.8.3.1

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