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From:   Steven Lee <steven_lee@aspeedtech.com>
To:     Linus Walleij <linus.walleij@linaro.org>,
        Bartosz Golaszewski <bgolaszewski@baylibre.com>,
        Rob Herring <robh+dt@kernel.org>,
        Joel Stanley <joel@jms.id.au>,
        Andrew Jeffery <andrew@aj.id.au>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@vger.kernel.org>,
        "moderated list:ARM/ASPEED MACHINE SUPPORT" 
        <linux-arm-kernel@lists.infradead.org>,
        "moderated list:ARM/ASPEED MACHINE SUPPORT" 
        <linux-aspeed@lists.ozlabs.org>,
        open list <linux-kernel@vger.kernel.org>
CC:     <steven_lee@aspeedtech.com>, <Hongweiz@ami.com>,
        <ryan_chen@aspeedtech.com>, <billy_tsai@aspeedtech.com>
Subject: [PATCH v5 10/10] gpio: gpio-aspeed-sgpio: Return error if ngpios is not multiple of 8.
Date:   Tue, 8 Jun 2021 18:25:45 +0800
Message-ID: <20210608102547.4880-11-steven_lee@aspeedtech.com>
In-Reply-To: <20210608102547.4880-1-steven_lee@aspeedtech.com>
References: <20210608102547.4880-1-steven_lee@aspeedtech.com>
MIME-Version: 1.0
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Precedence: bulk

Add an else-if condition in the probe function to check whether ngpios is
multiple of 8.
Per AST datasheet, numbers of available serial GPIO pins in Serial GPIO
Configuration Register must be n bytes. For instance, if n = 1, it means
AST SoC supports 8 GPIO pins.

Signed-off-by: Steven Lee <steven_lee@aspeedtech.com>
---
 drivers/gpio/gpio-aspeed-sgpio.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpio/gpio-aspeed-sgpio.c b/drivers/gpio/gpio-aspeed-sgpio.c
index f1e40486d401..1a3fcc721664 100644
--- a/drivers/gpio/gpio-aspeed-sgpio.c
+++ b/drivers/gpio/gpio-aspeed-sgpio.c
@@ -572,6 +572,10 @@ static int __init aspeed_sgpio_probe(struct platform_device *pdev)
 		dev_err(&pdev->dev, "Number of GPIOs exceeds the maximum of %d: %d\n",
 			gpio->max_ngpios, nr_gpios);
 		return -EINVAL;
+	} else if (nr_gpios % 8) {
+		dev_err(&pdev->dev, "Number of GPIOs not multiple of 8: %d\n",
+			nr_gpios);
+		return -EINVAL;
 	}
 	gpio->n_sgpio = nr_gpios;
 
-- 
2.17.1