linux-kernel - [PATCH AUTOSEL 4.18 112/136] spi: orion: fix CS GPIO handling again

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Message-ID: <20180917030006.245495-112-alexander.levin@microsoft.com>
Date:   Mon, 17 Sep 2018 03:01:22 +0000
From:   Sasha Levin <Alexander.Levin@...rosoft.com>
To:     "stable@...r.kernel.org" <stable@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     Jan Kundrát <jan.kundrat@...net.cz>,
        Mark Brown <broonie@...nel.org>,
        Sasha Levin <Alexander.Levin@...rosoft.com>
Subject: [PATCH AUTOSEL 4.18 112/136] spi: orion: fix CS GPIO handling again

From: Jan Kundrát <jan.kundrat@...net.cz>

[ Upstream commit fb9acf5f1f21f1de193523ff780bda375b4c2e21 ]

The code did not de-assert any CS GPIOs before probing slaves. This
means that several CS signals could be active at once, garbling the
communication. Whether this was actually a problem depended on the type
of the SPI device attached (so my "spidev" for userspace access worked
correctly because its probe was effectively a no-op), and on the state
of the GPIO pins at SoC's boot.

The code was already iterating through all DT children of the SPI
controller, so this change re-uses that loop for CS GPIO setup as well.
This means that this might change the number of the HW CS signal which
is picked for all GPIO CS devices. Previously, the lowest one was used,
but we now use the first one from the DT.

With this move of the code, we can also finally initialize each GPIO CS
lane before registering the SPI controller (which in turn probes for
slaves).

I tried to fix this in 544248623b95 already, but that only did it half
way by registering the GPIOs properly. That patch failed to set their
logic signals early enough, though.

Signed-off-by: Jan Kundrát <jan.kundrat@...net.cz>
Signed-off-by: Mark Brown <broonie@...nel.org>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
---
 drivers/spi/spi-orion.c | 77 +++++++++++++++++++++--------------------
 1 file changed, 40 insertions(+), 37 deletions(-)

diff --git a/drivers/spi/spi-orion.c b/drivers/spi/spi-orion.c
index d01a6adc726e..47ef6b1a2e76 100644
--- a/drivers/spi/spi-orion.c
+++ b/drivers/spi/spi-orion.c
@@ -20,6 +20,7 @@
 #include <linux/of.h>
 #include <linux/of_address.h>
 #include <linux/of_device.h>
+#include <linux/of_gpio.h>
 #include <linux/clk.h>
 #include <linux/sizes.h>
 #include <linux/gpio.h>
@@ -681,9 +682,9 @@ static int orion_spi_probe(struct platform_device *pdev)
 		goto out_rel_axi_clk;
 	}
 
-	/* Scan all SPI devices of this controller for direct mapped devices */
 	for_each_available_child_of_node(pdev->dev.of_node, np) {
 		u32 cs;
+		int cs_gpio;
 
 		/* Get chip-select number from the "reg" property */
 		status = of_property_read_u32(np, "reg", &cs);
@@ -694,6 +695,44 @@ static int orion_spi_probe(struct platform_device *pdev)
 			continue;
 		}
 
+		/*
+		 * Initialize the CS GPIO:
+		 * - properly request the actual GPIO signal
+		 * - de-assert the logical signal so that all GPIO CS lines
+		 *   are inactive when probing for slaves
+		 * - find an unused physical CS which will be driven for any
+		 *   slave which uses a CS GPIO
+		 */
+		cs_gpio = of_get_named_gpio(pdev->dev.of_node, "cs-gpios", cs);
+		if (cs_gpio > 0) {
+			char *gpio_name;
+			int cs_flags;
+
+			if (spi->unused_hw_gpio == -1) {
+				dev_info(&pdev->dev,
+					"Selected unused HW CS#%d for any GPIO CSes\n",
+					cs);
+				spi->unused_hw_gpio = cs;
+			}
+
+			gpio_name = devm_kasprintf(&pdev->dev, GFP_KERNEL,
+					"%s-CS%d", dev_name(&pdev->dev), cs);
+			if (!gpio_name) {
+				status = -ENOMEM;
+				goto out_rel_axi_clk;
+			}
+
+			cs_flags = of_property_read_bool(np, "spi-cs-high") ?
+				GPIOF_OUT_INIT_LOW : GPIOF_OUT_INIT_HIGH;
+			status = devm_gpio_request_one(&pdev->dev, cs_gpio,
+					cs_flags, gpio_name);
+			if (status) {
+				dev_err(&pdev->dev,
+					"Can't request GPIO for CS %d\n", cs);
+				goto out_rel_axi_clk;
+			}
+		}
+
 		/*
 		 * Check if an address is configured for this SPI device. If
 		 * not, the MBus mapping via the 'ranges' property in the 'soc'
@@ -740,44 +779,8 @@ static int orion_spi_probe(struct platform_device *pdev)
 	if (status < 0)
 		goto out_rel_pm;
 
-	if (master->cs_gpios) {
-		int i;
-		for (i = 0; i < master->num_chipselect; ++i) {
-			char *gpio_name;
-
-			if (!gpio_is_valid(master->cs_gpios[i])) {
-				continue;
-			}
-
-			gpio_name = devm_kasprintf(&pdev->dev, GFP_KERNEL,
-					"%s-CS%d", dev_name(&pdev->dev), i);
-			if (!gpio_name) {
-				status = -ENOMEM;
-				goto out_rel_master;
-			}
-
-			status = devm_gpio_request(&pdev->dev,
-					master->cs_gpios[i], gpio_name);
-			if (status) {
-				dev_err(&pdev->dev,
-					"Can't request GPIO for CS %d\n",
-					master->cs_gpios[i]);
-				goto out_rel_master;
-			}
-			if (spi->unused_hw_gpio == -1) {
-				dev_info(&pdev->dev,
-					"Selected unused HW CS#%d for any GPIO CSes\n",
-					i);
-				spi->unused_hw_gpio = i;
-			}
-		}
-	}
-
-
 	return status;
 
-out_rel_master:
-	spi_unregister_master(master);
 out_rel_pm:
 	pm_runtime_disable(&pdev->dev);
 out_rel_axi_clk:
-- 
2.17.1