Char/Misc driver fixes for 5.19-rc3

Here are some small char/misc driver fixes for 5.19-rc3 that resolve
 some reported issues.
 
 They include:
 	- mei driver fixes
 	- comedi driver fix
 	- rtsx build warning fix
 	- fsl-mc-bus driver fix
 
 All of these have been in linux-next for a while with no reported
 issues.
 
 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'char-misc-5.19-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc

Pull char/misc driver fixes from Greg KH:
 "Here are some small char/misc driver fixes for 5.19-rc3 that resolve
  some reported issues.

  They include:

   - mei driver fixes

   - comedi driver fix

   - rtsx build warning fix

   - fsl-mc-bus driver fix

  All of these have been in linux-next for a while with no reported
  issues"

* tag 'char-misc-5.19-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc:
  eeprom: at25: Split reads into chunks and cap write size
  misc: atmel-ssc: Fix IRQ check in ssc_probe
  char: lp: remove redundant initialization of err

drivers/char/lp.c

@@ -1019,7 +1019,7 @@ static struct parport_driver lp_driver = {
 
 static int __init lp_init(void)
 {
-	int i, err = 0;
+	int i, err;
 
 	if (parport_nr[0] == LP_PARPORT_OFF)
 		return 0;

drivers/misc/atmel-ssc.c

@@ -232,9 +232,9 @@ static int ssc_probe(struct platform_device *pdev)
 	clk_disable_unprepare(ssc->clk);
 
 	ssc->irq = platform_get_irq(pdev, 0);
-	if (!ssc->irq) {
+	if (ssc->irq < 0) {
 		dev_dbg(&pdev->dev, "could not get irq\n");
-		return -ENXIO;
+		return ssc->irq;
 	}
 
 	mutex_lock(&user_lock);

drivers/misc/eeprom/at25.c

@@ -79,6 +79,11 @@ static int at25_ee_read(void *priv, unsigned int offset,
 {
 	struct at25_data *at25 = priv;
 	char *buf = val;
+	size_t max_chunk = spi_max_transfer_size(at25->spi);
+	size_t num_msgs = DIV_ROUND_UP(count, max_chunk);
+	size_t nr_bytes = 0;
+	unsigned int msg_offset;
+	size_t msg_count;
 	u8			*cp;
 	ssize_t			status;
 	struct spi_transfer	t[2];
@@ -92,54 +97,59 @@ static int at25_ee_read(void *priv, unsigned int offset,
 	if (unlikely(!count))
 		return -EINVAL;
 
-	cp = at25->command;
+	msg_offset = (unsigned int)offset;
+	msg_count = min(count, max_chunk);
+	while (num_msgs) {
+		cp = at25->command;
 
-	instr = AT25_READ;
-	if (at25->chip.flags & EE_INSTR_BIT3_IS_ADDR)
-		if (offset >= BIT(at25->addrlen * 8))
-			instr |= AT25_INSTR_BIT3;
+		instr = AT25_READ;
+		if (at25->chip.flags & EE_INSTR_BIT3_IS_ADDR)
+			if (msg_offset >= BIT(at25->addrlen * 8))
+				instr |= AT25_INSTR_BIT3;
 
-	mutex_lock(&at25->lock);
+		mutex_lock(&at25->lock);
 
-	*cp++ = instr;
+		*cp++ = instr;
 
-	/* 8/16/24-bit address is written MSB first */
-	switch (at25->addrlen) {
-	default:	/* case 3 */
-		*cp++ = offset >> 16;
-		fallthrough;
-	case 2:
-		*cp++ = offset >> 8;
-		fallthrough;
-	case 1:
-	case 0:	/* can't happen: for better code generation */
-		*cp++ = offset >> 0;
+		/* 8/16/24-bit address is written MSB first */
+		switch (at25->addrlen) {
+		default:	/* case 3 */
+			*cp++ = msg_offset >> 16;
+			fallthrough;
+		case 2:
+			*cp++ = msg_offset >> 8;
+			fallthrough;
+		case 1:
+		case 0:	/* can't happen: for better code generation */
+			*cp++ = msg_offset >> 0;
+		}
+
+		spi_message_init(&m);
+		memset(t, 0, sizeof(t));
+
+		t[0].tx_buf = at25->command;
+		t[0].len = at25->addrlen + 1;
+		spi_message_add_tail(&t[0], &m);
+
+		t[1].rx_buf = buf + nr_bytes;
+		t[1].len = msg_count;
+		spi_message_add_tail(&t[1], &m);
+
+		status = spi_sync(at25->spi, &m);
+
+		mutex_unlock(&at25->lock);
+
+		if (status)
+			return status;
+
+		--num_msgs;
+		msg_offset += msg_count;
+		nr_bytes += msg_count;
 	}
 
-	spi_message_init(&m);
-	memset(t, 0, sizeof(t));
-
-	t[0].tx_buf = at25->command;
-	t[0].len = at25->addrlen + 1;
-	spi_message_add_tail(&t[0], &m);
-
-	t[1].rx_buf = buf;
-	t[1].len = count;
-	spi_message_add_tail(&t[1], &m);
-
-	/*
-	 * Read it all at once.
-	 *
-	 * REVISIT that's potentially a problem with large chips, if
-	 * other devices on the bus need to be accessed regularly or
-	 * this chip is clocked very slowly.
-	 */
-	status = spi_sync(at25->spi, &m);
-	dev_dbg(&at25->spi->dev, "read %zu bytes at %d --> %zd\n",
-		count, offset, status);
-
-	mutex_unlock(&at25->lock);
-	return status;
+	dev_dbg(&at25->spi->dev, "read %zu bytes at %d\n",
+		count, offset);
+	return 0;
 }
 
 /* Read extra registers as ID or serial number */
@@ -190,6 +200,7 @@ ATTRIBUTE_GROUPS(sernum);
 static int at25_ee_write(void *priv, unsigned int off, void *val, size_t count)
 {
 	struct at25_data *at25 = priv;
+	size_t maxsz = spi_max_transfer_size(at25->spi);
 	const char *buf = val;
 	int			status = 0;
 	unsigned		buf_size;
@@ -253,6 +264,8 @@ static int at25_ee_write(void *priv, unsigned int off, void *val, size_t count)
 		segment = buf_size - (offset % buf_size);
 		if (segment > count)
 			segment = count;
+		if (segment > maxsz)
+			segment = maxsz;
 		memcpy(cp, buf, segment);
 		status = spi_write(at25->spi, bounce,
 				segment + at25->addrlen + 1);