From c3fbb1e6771dabb14571552c036a049ffa470eb1 Mon Sep 17 00:00:00 2001
From: Phil Elwell <phil@raspberrypi.com>
Date: Fri, 30 Apr 2021 08:34:36 +0100
Subject: [PATCH] spi: bcm2835: Increase the CS limit to 24

Increase the maximum number of CS lines to 24, and ensure this limit is
not exceeded.

See: https://github.com/raspberrypi/linux/pull/4281

Suggested-by: Joe Burmeister <joe.burmeister@devtank.co.uk>
Signed-off-by: Phil Elwell <phil@raspberrypi.com>
---
 drivers/spi/spi-bcm2835.c | 6 ++++++
 1 file changed, 6 insertions(+)

--- a/drivers/spi/spi-bcm2835.c
+++ b/drivers/spi/spi-bcm2835.c
@@ -28,6 +28,7 @@
 #include <linux/gpio/consumer.h>
 #include <linux/gpio/machine.h> /* FIXME: using chip internals */
 #include <linux/gpio/driver.h> /* FIXME: using chip internals */
+#include <linux/of_gpio.h>
 #include <linux/of_irq.h>
 #include <linux/spi/spi.h>
 
@@ -1303,6 +1304,11 @@ static int bcm2835_spi_probe(struct plat
 	struct bcm2835_spi *bs;
 	int err;
 
+	if (of_gpio_named_count(pdev->dev.of_node, "cs-gpios") >
+	    BCM2835_SPI_NUM_CS)
+		return dev_err_probe(&pdev->dev, -EINVAL,
+				     "too many chip selects\n");
+
 	ctlr = devm_spi_alloc_master(&pdev->dev, ALIGN(sizeof(*bs),
 						  dma_get_cache_alignment()));
 	if (!ctlr)
