sfc: Clean up waits for flash/EEPROM operations

Make falcon_spi_wait() ignore the write timer - it is only relevant to
write commands, it only works for the device that contains VPD, and it
might not be initialised properly at all.

Rename falcon_spi_fast_wait() to falcon_spi_wait_write(), reflecting
its use, and make it wait up to 10 ms (not 1 ms) since buffered writes
to EEPROM may take this long to complete.

Make both wait functions sleep instead of busy-waiting.

Replace wait for command completion at top of falcon_spi_cmd() with a
single poll; no command should be running when the function starts.

Correct some comments.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 39 insertions, 23 deletions

diff --git a/drivers/net/sfc/falcon.c b/drivers/net/sfc/falcon.c
index 1d160daf83bb..511308560487 100644
--- a/drivers/net/sfc/falcon.c
+++ b/drivers/net/sfc/falcon.c
@@ -1607,24 +1607,37 @@ void falcon_fini_interrupt(struct efx_nic *efx)
 
 #define FALCON_SPI_MAX_LEN sizeof(efx_oword_t)
 
+static int falcon_spi_poll(struct efx_nic *efx)
+{
+        efx_oword_t reg;
+        falcon_read(efx, &reg, EE_SPI_HCMD_REG_KER);
+        return EFX_OWORD_FIELD(reg, EE_SPI_HCMD_CMD_EN) ? -EBUSY : 0;
+}
+
 /* Wait for SPI command completion */
 static int falcon_spi_wait(struct efx_nic *efx)
 {
-        unsigned long timeout = jiffies + DIV_ROUND_UP(HZ, 10);
-        efx_oword_t reg;
-        bool cmd_en, timer_active;
+        /* Most commands will finish quickly, so we start polling at
+         * very short intervals.  Sometimes the command may have to
+         * wait for VPD or expansion ROM access outside of our
+         * control, so we allow up to 100 ms. */
+        unsigned long timeout = jiffies + 1 + DIV_ROUND_UP(HZ, 10);
+        int i;
+
+        for (i = 0; i < 10; i++) {
+                if (!falcon_spi_poll(efx))
+                        return 0;
+                udelay(10);
+        }
 
         for (;;) {
-                falcon_read(efx, &reg, EE_SPI_HCMD_REG_KER);
-                cmd_en = EFX_OWORD_FIELD(reg, EE_SPI_HCMD_CMD_EN);
-                timer_active = EFX_OWORD_FIELD(reg, EE_WR_TIMER_ACTIVE);
-                if (!cmd_en && !timer_active)
+                if (!falcon_spi_poll(efx))
                         return 0;
                 if (time_after_eq(jiffies, timeout)) {
                         EFX_ERR(efx, "timed out waiting for SPI\n");
                         return -ETIMEDOUT;
                 }
-                cpu_relax();
+                schedule_timeout_uninterruptible(1);
         }
 }
 
@@ -1643,8 +1656,8 @@ int falcon_spi_cmd(const struct efx_spi_device *spi,
                 return -EINVAL;
         BUG_ON(!mutex_is_locked(&efx->spi_lock));
 
-        /* Check SPI not currently being accessed */
-        rc = falcon_spi_wait(efx);
+        /* Check that previous command is not still running */
+        rc = falcon_spi_poll(efx);
         if (rc)
                 return rc;
 
@@ -1700,26 +1713,29 @@ efx_spi_munge_command(const struct efx_spi_device *spi,
         return command | (((address >> 8) & spi->munge_address) << 3);
 }
 
-int falcon_spi_fast_wait(const struct efx_spi_device *spi)
+/* Wait up to 10 ms for buffered write completion */
+int falcon_spi_wait_write(const struct efx_spi_device *spi)
 {
+        struct efx_nic *efx = spi->efx;
+        unsigned long timeout = jiffies + 1 + DIV_ROUND_UP(HZ, 100);
         u8 status;
-        int i, rc;
-
-        /* Wait up to 1000us for flash/EEPROM to finish a fast operation. */
-        for (i = 0; i < 50; i++) {
-                udelay(20);
+        int rc;
 
+        for (;;) {
                 rc = falcon_spi_cmd(spi, SPI_RDSR, -1, NULL,
                                     &status, sizeof(status));
                 if (rc)
                         return rc;
                 if (!(status & SPI_STATUS_NRDY))
                         return 0;
+                if (time_after_eq(jiffies, timeout)) {
+                        EFX_ERR(efx, "SPI write timeout on device %d"
+                                " last status=0x%02x\n",
+                                spi->device_id, status);
+                        return -ETIMEDOUT;
+                }
+                schedule_timeout_uninterruptible(1);
         }
-        EFX_ERR(spi->efx,
-                "timed out waiting for device %d last status=0x%02x\n",
-                spi->device_id, status);
-        return -ETIMEDOUT;
 }
 
 int falcon_spi_read(const struct efx_spi_device *spi, loff_t start,
@@ -1773,7 +1789,7 @@ int falcon_spi_write(const struct efx_spi_device *spi, loff_t start,
                 if (rc)
                         break;
 
-                rc = falcon_spi_fast_wait(spi);
+                rc = falcon_spi_wait_write(spi);
                 if (rc)
                         break;
 
diff --git a/drivers/net/sfc/mtd.c b/drivers/net/sfc/mtd.c
index a1e6c2875fc0..665cafb88d6a 100644
--- a/drivers/net/sfc/mtd.c
+++ b/drivers/net/sfc/mtd.c
@@ -76,7 +76,7 @@ static int efx_spi_unlock(const struct efx_spi_device *spi)
         rc = falcon_spi_cmd(spi, SPI_WRSR, -1, &status, NULL, sizeof(status));
         if (rc)
                 return rc;
-        rc = falcon_spi_fast_wait(spi);
+        rc = falcon_spi_wait_write(spi);
         if (rc)
                 return rc;
 
diff --git a/drivers/net/sfc/spi.h b/drivers/net/sfc/spi.h
index 38e22ff4d7af..1b1ceb411671 100644
--- a/drivers/net/sfc/spi.h
+++ b/drivers/net/sfc/spi.h
@@ -69,7 +69,7 @@ struct efx_spi_device {
 
 int falcon_spi_cmd(const struct efx_spi_device *spi, unsigned int command,
                    int address, const void* in, void *out, size_t len);
-int falcon_spi_fast_wait(const struct efx_spi_device *spi);
+int falcon_spi_wait_write(const struct efx_spi_device *spi);
 int falcon_spi_read(const struct efx_spi_device *spi, loff_t start,
                     size_t len, size_t *retlen, u8 *buffer);
 int falcon_spi_write(const struct efx_spi_device *spi, loff_t start,