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[130.75.33.87]) by smtp.gmail.com with ESMTPSA id du16sm999619ejc.42.2021.06.10.06.24.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 10 Jun 2021 06:24:58 -0700 (PDT) From: Andreas Kaessens To: linus.walleij@linaro.org, robh+dt@kernel.org, linux-gpio@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org Cc: linux-kernel@i4.cs.fau.de, Andreas Kaessens , Darian Biastoch Subject: [PATCH 1/2] pinctrl: mcp23s08: Add optional reset GPIO Date: Thu, 10 Jun 2021 15:24:37 +0200 Message-Id: <20210610132438.3085841-1-akaessens@gmail.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-gpio@vger.kernel.org The MCP23x port expander RESET# line can be connected to a host GPIO. The optional reset-gpio must be set to LOW if the reset is asserted at probing time. On page 5 in the datasheet [0] the "Device Active After Reset high" time is specified at 0 µs. Therefore no waiting is needed after the reset transition. [0] https://ww1.microchip.com/downloads/en/DeviceDoc/20001952C.pdf Signed-off-by: Andreas Kaessens Signed-off-by: Darian Biastoch --- drivers/pinctrl/pinctrl-mcp23s08.c | 3 +++ drivers/pinctrl/pinctrl-mcp23s08.h | 1 + 2 files changed, 4 insertions(+) diff --git a/drivers/pinctrl/pinctrl-mcp23s08.c b/drivers/pinctrl/pinctrl-mcp23s08.c index 799d596a1a4b..8ab254170d99 100644 --- a/drivers/pinctrl/pinctrl-mcp23s08.c +++ b/drivers/pinctrl/pinctrl-mcp23s08.c @@ -9,6 +9,7 @@ #include #include #include +#include #include #include #include @@ -558,6 +559,8 @@ int mcp23s08_probe_one(struct mcp23s08 *mcp, struct device *dev, mcp->chip.parent = dev; mcp->chip.owner = THIS_MODULE; + mcp->reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_LOW); + /* verify MCP_IOCON.SEQOP = 0, so sequential reads work, * and MCP_IOCON.HAEN = 1, so we work with all chips. */ diff --git a/drivers/pinctrl/pinctrl-mcp23s08.h b/drivers/pinctrl/pinctrl-mcp23s08.h index 90dc27081a3c..b8d15939e0c2 100644 --- a/drivers/pinctrl/pinctrl-mcp23s08.h +++ b/drivers/pinctrl/pinctrl-mcp23s08.h @@ -43,6 +43,7 @@ struct mcp23s08 { struct pinctrl_dev *pctldev; struct pinctrl_desc pinctrl_desc; + struct gpio_desc *reset_gpio; }; extern const struct regmap_config mcp23x08_regmap; -- 2.25.1