sleep briefly while flashing

Summary:
Go idle periodically when flashing the image, to allow other work
on the system to happen, for example SPI I/O.  For a 32MB flash
image, this would result in an extra 8s of idle time during wipe plus
8s during flashing.  For S434121.

Test Plan:
```
0 ~/local/openbmc/tools/flashy $ ./build.sh && ./build_dev.sh && go test ./...
?       github.com/facebook/openbmc/tools/flashy/flash_procedure        [no test files]
?       github.com/facebook/openbmc/tools/flashy/lib/logger     [no test files]
?       github.com/facebook/openbmc/tools/flashy/tests  [no test files]
?       github.com/facebook/openbmc/tools/flashy/utilities      [no test files]
ok      github.com/facebook/openbmc/tools/flashy        2.024s
ok      github.com/facebook/openbmc/tools/flashy/checks_and_remediations/bletchley      (cached)
ok      github.com/facebook/openbmc/tools/flashy/checks_and_remediations/common (cached)
ok      github.com/facebook/openbmc/tools/flashy/checks_and_remediations/galaxy100      (cached)
ok      github.com/facebook/openbmc/tools/flashy/checks_and_remediations/grandteton     (cached)
ok      github.com/facebook/openbmc/tools/flashy/checks_and_remediations/wedge100       (cached)
ok      github.com/facebook/openbmc/tools/flashy/checks_and_remediations/yamp   (cached)
ok      github.com/facebook/openbmc/tools/flashy/install        0.007s
ok      github.com/facebook/openbmc/tools/flashy/lib/fileutils  (cached)
ok      github.com/facebook/openbmc/tools/flashy/lib/flash      0.007s
ok      github.com/facebook/openbmc/tools/flashy/lib/flash/flashcp      0.508s
ok      github.com/facebook/openbmc/tools/flashy/lib/flash/flashutils   (cached)
ok      github.com/facebook/openbmc/tools/flashy/lib/flash/flashutils/devices   (cached)
ok      github.com/facebook/openbmc/tools/flashy/lib/step       (cached)
ok      github.com/facebook/openbmc/tools/flashy/lib/utils      (cached)
ok      github.com/facebook/openbmc/tools/flashy/lib/validate   (cached)
ok      github.com/facebook/openbmc/tools/flashy/lib/validate/image     (cached)
ok      github.com/facebook/openbmc/tools/flashy/lib/validate/partition (cached)
0 ~/local/openbmc/tools/flashy $
```

Build ephemeral fbpkg and flash a wedge100 using it:

```
Host                                Workflow ID                           Progress    Status                   Result
----------------------------------  ------------------------------------  ----------  -----------------------  ----------------------
fboss8382003-oob.snc1.facebook.com  b4600065-e674-4696-9378-5c313ae45819  finished    WorkflowStatus.FINISHED  FinishStatus.SUCCEEDED
```
-> https://fburl.com/scuba/openbmc_upgrades/yksvon8b

Reviewed By: kawmarco

Differential Revision: D59927810

fbshipit-source-id: 7db5bb534575d360816a2ec27bea361936fe16dd

tools/flashy/lib/flash/flashcp/flashcp.go

@@ -41,6 +41,7 @@ import (
 	"os"
 	"regexp"
 	"syscall"
+	"time"
 	"unsafe"
 
 	"github.com/facebook/openbmc/tools/flashy/lib/fileutils"
@@ -83,6 +84,7 @@ type mtd_info_user struct {
 
 const sizeof_mtd_info_user = 32
 const sizeof_erase_user_info = 8
+const chunkSize = uint32(1048576)
 
 // linux/include/uapi/mtd/mtd-abi.h
 var MEMGETINFO = ioctl.IOR('M', 1, sizeof_mtd_info_user)
@@ -254,6 +256,8 @@ var eraseFlashDevice = func(
 	imFile imageFile,
 	roOffset uint32,
 ) error {
+	sleepTodo := int32(chunkSize)
+
 	log.Printf("Erasing flash device '%v'...", deviceFile.Name())
 
 	if m.erasesize == 0 {
@@ -293,6 +297,18 @@ var eraseFlashDevice = func(
 			log.Print(errMsg)
 			return errors.Errorf("%v", errMsg)
 		}
+
+		// For every chunkSize bytes of work done, sleep for 1/4s to
+		// allow for other work on the system (especially I/O to the
+		// SPI) to complete.
+		//
+		// In practice erasesize will be smaller than chunkSize but
+		// in any case this will still trigger every so often.
+		sleepTodo = sleepTodo - int32(m.erasesize);
+		if sleepTodo <= 0 {
+			sleepTodo = int32(chunkSize);
+			utils.Sleep(time.Millisecond * 250);
+		}
 	}
 
 	log.Printf("Finished erasing flash device '%v'", deviceFile.Name())
@@ -306,7 +322,6 @@ var flashImage = func(
 	imFile imageFile,
 	roOffset uint32,
 ) error {
-	const chunkSize = uint32(1048576)
 	fileSize := uint32(len(imFile.data))
 
 	log.Printf("Flashing image '%v' on to flash device '%v'", imFile.name, deviceFile.Name())
@@ -336,6 +351,11 @@ var flashImage = func(
 				imFile.name, deviceFile.Name(), n, err,
 			)
 		}
+
+		// For every chunkSize bytes of work done, sleep for 1/4s to
+		// allow for other work on the system (especially I/O to the
+		// SPI) to complete.
+		utils.Sleep(time.Millisecond * 250);
 	}
 
 	log.Printf("Finished flashing image '%v' on to flash device '%v'",

tools/flashy/lib/flash/flashcp/flashcp_test.go

@@ -23,6 +23,7 @@ import (
 	"bytes"
 	"math"
 	"testing"
+	"time"
 	"unsafe"
 
 	"github.com/facebook/openbmc/tools/flashy/lib/fileutils"
@@ -59,6 +60,7 @@ func TestFlashCp(t *testing.T) {
 	runFlashProcessOrig := runFlashProcess
 	closeFileOrig := closeFlashDeviceFile
 	PetWatchdogOrig := utils.PetWatchdog
+	sleepOrig := utils.Sleep
 	defer func() {
 		openFlashDeviceFile = openFileOrig
 		getMtdInfoUser = getMtdInfoUserOrig
@@ -67,6 +69,7 @@ func TestFlashCp(t *testing.T) {
 		runFlashProcess = runFlashProcessOrig
 		closeFlashDeviceFile = closeFileOrig
 		utils.PetWatchdog = PetWatchdogOrig
+		utils.Sleep = sleepOrig
 	}()
 
 	cases := []struct {
@@ -168,6 +171,7 @@ func TestFlashCp(t *testing.T) {
 	}
 	utils.PetWatchdog = func() {
 	}
+	utils.Sleep = func(t time.Duration) {}
 
 	for _, tc := range cases {
 		t.Run(tc.name, func(t *testing.T) {
@@ -227,6 +231,7 @@ func TestRunFlashProcess(t *testing.T) {
 	flashImageOrig := flashImage
 	verifyFlashOrig := verifyFlash
 	PetWatchdogOrig := utils.PetWatchdog
+	sleepOrig := utils.Sleep
 	defer func() {
 		openFlashDeviceFile = openFlashDeviceFileOrig
 		closeFlashDeviceFile = closeFlashDeviceFileOrig
@@ -235,6 +240,7 @@ func TestRunFlashProcess(t *testing.T) {
 		flashImage = flashImageOrig
 		verifyFlash = verifyFlashOrig
 		utils.PetWatchdog = PetWatchdogOrig
+		utils.Sleep = sleepOrig
 	}()
 
 	cases := []struct {
@@ -298,6 +304,7 @@ func TestRunFlashProcess(t *testing.T) {
 	}
 	utils.PetWatchdog = func() {
 	}
+	utils.Sleep = func(t time.Duration) {}
 
 	for _, tc := range cases {
 		t.Run(tc.name, func(t *testing.T) {
@@ -441,8 +448,10 @@ func TestHealthCheck(t *testing.T) {
 
 func TestEraseFlashDevice(t *testing.T) {
 	IOCTLOrig := IOCTL
+	sleepOrig := utils.Sleep
 	defer func() {
 		IOCTL = IOCTLOrig
+		utils.Sleep = sleepOrig
 	}()
 
 	imData := []byte("foobar")
@@ -529,6 +538,7 @@ func TestEraseFlashDevice(t *testing.T) {
 	fileutils.Munmap = func(data []byte) error {
 		return nil
 	}
+	utils.Sleep = func(t time.Duration) {}
 
 	for _, tc := range cases {
 		t.Run(tc.name, func(t *testing.T) {
@@ -566,8 +576,10 @@ func TestEraseFlashDevice(t *testing.T) {
 
 func TestFlashImage(t *testing.T) {
 	pwriteOrig := fileutils.Pwrite
+	sleepOrig := utils.Sleep
 	defer func() {
 		fileutils.Pwrite = pwriteOrig
+		utils.Sleep = sleepOrig
 	}()
 
 	imData := []byte("foobar")
@@ -610,6 +622,9 @@ func TestFlashImage(t *testing.T) {
 			want:     errors.Errorf("roOffset (100) >= file size (6)"),
 		},
 	}
+
+	utils.Sleep = func(t time.Duration) {}
+
 	for _, tc := range cases {
 		t.Run(tc.name, func(t *testing.T) {
 			fileutils.Pwrite = func(fd int, p []byte, roOffset int64) (n int, err error) {
@@ -642,13 +657,16 @@ func TestFlashImage(t *testing.T) {
 func TestVerifyFlash(t *testing.T) {
 	mmapFileRangeOrig := fileutils.MmapFileRange
 	munmapOrig := fileutils.Munmap
+	sleepOrig := utils.Sleep
 	defer func() {
 		fileutils.MmapFileRange = mmapFileRangeOrig
 		fileutils.Munmap = munmapOrig
+		utils.Sleep = sleepOrig
 	}()
 	fileutils.Munmap = func(b []byte) error {
 		return nil
 	}
+	utils.Sleep = func(t time.Duration) {}
 
 	imData := []byte("foobar")
 	imFile := imageFile{