sfc: Handle firmware assertion failure while resetting

This allows the driver to recover if the MC firmware has crashed due
to an assertion failure.

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

2 files changed, 44 insertions, 25 deletions

diff --git a/drivers/net/sfc/mcdi.c b/drivers/net/sfc/mcdi.c
index 9f035b9f0350..e9f0e5ee4519 100644
--- a/drivers/net/sfc/mcdi.c
+++ b/drivers/net/sfc/mcdi.c
@@ -896,29 +896,27 @@ fail:
         return rc;
 }
 
-int efx_mcdi_handle_assertion(struct efx_nic *efx)
+static int efx_mcdi_read_assertion(struct efx_nic *efx)
 {
-        union {
-                u8 asserts[MC_CMD_GET_ASSERTS_IN_LEN];
-                u8 reboot[MC_CMD_REBOOT_IN_LEN];
-        } inbuf;
-        u8 assertion[MC_CMD_GET_ASSERTS_OUT_LEN];
+        u8 inbuf[MC_CMD_GET_ASSERTS_IN_LEN];
+        u8 outbuf[MC_CMD_GET_ASSERTS_OUT_LEN];
         unsigned int flags, index, ofst;
         const char *reason;
         size_t outlen;
         int retry;
         int rc;
 
-        /* Check if the MC is in the assertion handler, retrying twice. Once
+        /* Attempt to read any stored assertion state before we reboot
+         * the mcfw out of the assertion handler. Retry twice, once
          * because a boot-time assertion might cause this command to fail
          * with EINTR. And once again because GET_ASSERTS can race with
          * MC_CMD_REBOOT running on the other port. */
         retry = 2;
         do {
-                MCDI_SET_DWORD(inbuf.asserts, GET_ASSERTS_IN_CLEAR, 0);
+                MCDI_SET_DWORD(inbuf, GET_ASSERTS_IN_CLEAR, 1);
                 rc = efx_mcdi_rpc(efx, MC_CMD_GET_ASSERTS,
-                                  inbuf.asserts, MC_CMD_GET_ASSERTS_IN_LEN,
-                                  assertion, sizeof(assertion), &outlen);
+                                  inbuf, MC_CMD_GET_ASSERTS_IN_LEN,
+                                  outbuf, sizeof(outbuf), &outlen);
         } while ((rc == -EINTR || rc == -EIO) && retry-- > 0);
 
         if (rc)
@@ -926,21 +924,11 @@ int efx_mcdi_handle_assertion(struct efx_nic *efx)
         if (outlen < MC_CMD_GET_ASSERTS_OUT_LEN)
                 return -EINVAL;
 
-        flags = MCDI_DWORD(assertion, GET_ASSERTS_OUT_GLOBAL_FLAGS);
+        /* Print out any recorded assertion state */
+        flags = MCDI_DWORD(outbuf, GET_ASSERTS_OUT_GLOBAL_FLAGS);
         if (flags == MC_CMD_GET_ASSERTS_FLAGS_NO_FAILS)
                 return 0;
 
-        /* Reset the hardware atomically such that only one port with succeed.
-         * This command will succeed if a reboot is no longer required (because
-         * the other port did it first), but fail with EIO if it succeeds.
-         */
-        BUILD_BUG_ON(MC_CMD_REBOOT_OUT_LEN != 0);
-        MCDI_SET_DWORD(inbuf.reboot, REBOOT_IN_FLAGS,
-                       MC_CMD_REBOOT_FLAGS_AFTER_ASSERTION);
-        efx_mcdi_rpc(efx, MC_CMD_REBOOT, inbuf.reboot, MC_CMD_REBOOT_IN_LEN,
-                     NULL, 0, NULL);
-
-        /* Print out the assertion */
         reason = (flags == MC_CMD_GET_ASSERTS_FLAGS_SYS_FAIL)
                 ? "system-level assertion"
                 : (flags == MC_CMD_GET_ASSERTS_FLAGS_THR_FAIL)
@@ -949,20 +937,45 @@ int efx_mcdi_handle_assertion(struct efx_nic *efx)
                 ? "watchdog reset"
                 : "unknown assertion";
         EFX_ERR(efx, "MCPU %s at PC = 0x%.8x in thread 0x%.8x\n", reason,
-                MCDI_DWORD(assertion, GET_ASSERTS_OUT_SAVED_PC_OFFS),
-                MCDI_DWORD(assertion, GET_ASSERTS_OUT_THREAD_OFFS));
+                MCDI_DWORD(outbuf, GET_ASSERTS_OUT_SAVED_PC_OFFS),
+                MCDI_DWORD(outbuf, GET_ASSERTS_OUT_THREAD_OFFS));
 
         /* Print out the registers */
         ofst = MC_CMD_GET_ASSERTS_OUT_GP_REGS_OFFS_OFST;
         for (index = 1; index < 32; index++) {
                 EFX_ERR(efx, "R%.2d (?): 0x%.8x\n", index,
-                        MCDI_DWORD2(assertion, ofst));
+                        MCDI_DWORD2(outbuf, ofst));
                 ofst += sizeof(efx_dword_t);
         }
 
         return 0;
 }
 
+static void efx_mcdi_exit_assertion(struct efx_nic *efx)
+{
+        u8 inbuf[MC_CMD_REBOOT_IN_LEN];
+
+        /* Atomically reboot the mcfw out of the assertion handler */
+        BUILD_BUG_ON(MC_CMD_REBOOT_OUT_LEN != 0);
+        MCDI_SET_DWORD(inbuf, REBOOT_IN_FLAGS,
+                       MC_CMD_REBOOT_FLAGS_AFTER_ASSERTION);
+        efx_mcdi_rpc(efx, MC_CMD_REBOOT, inbuf, MC_CMD_REBOOT_IN_LEN,
+                     NULL, 0, NULL);
+}
+
+int efx_mcdi_handle_assertion(struct efx_nic *efx)
+{
+        int rc;
+
+        rc = efx_mcdi_read_assertion(efx);
+        if (rc)
+                return rc;
+
+        efx_mcdi_exit_assertion(efx);
+
+        return 0;
+}
+
 void efx_mcdi_set_id_led(struct efx_nic *efx, enum efx_led_mode mode)
 {
         u8 inbuf[MC_CMD_SET_ID_LED_IN_LEN];
diff --git a/drivers/net/sfc/siena.c b/drivers/net/sfc/siena.c
index f8c6771e66d8..0e4c13abf087 100644
--- a/drivers/net/sfc/siena.c
+++ b/drivers/net/sfc/siena.c
@@ -181,6 +181,12 @@ static int siena_test_registers(struct efx_nic *efx)
 
 static int siena_reset_hw(struct efx_nic *efx, enum reset_type method)
 {
+        int rc;
+
+        /* Recover from a failed assertion pre-reset */
+        rc = efx_mcdi_handle_assertion(efx);
+        if (rc)
+                return rc;
 
         if (method == RESET_TYPE_WORLD)
                 return efx_mcdi_reset_mc(efx);