From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steven Lee Date: Thu, 6 May 2021 18:03:09 +0800 Subject: [PATCH v3 2/5] ARM: dts: aspeed: ast2600evb: Add comment for gpio regulator of sdhci In-Reply-To: <20210506100312.1638-1-steven_lee@aspeedtech.com> References: <20210506100312.1638-1-steven_lee@aspeedtech.com> Message-ID: <20210506100312.1638-3-steven_lee@aspeedtech.com> List-Id: To: linux-aspeed@lists.ozlabs.org MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Add the description for describing the AST2600-A2 EVB reference design of GPIO regulators. Signed-off-by: Steven Lee --- arch/arm/boot/dts/aspeed-ast2600-evb.dts | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/arch/arm/boot/dts/aspeed-ast2600-evb.dts b/arch/arm/boot/dts/aspeed-ast2600-evb.dts index 2772796e215e..1ae0facc3d5f 100644 --- a/arch/arm/boot/dts/aspeed-ast2600-evb.dts +++ b/arch/arm/boot/dts/aspeed-ast2600-evb.dts @@ -104,6 +104,21 @@ status = "okay"; }; +/* + * The signal voltage of sdhci0 and sdhci1 on AST2600-A2 EVB is able to be + * toggled by GPIO pins. + * In the reference design, GPIOV0 of AST2600-A2 EVB is connected to the + * power load switch that providing 3.3v to sdhci0 vdd, GPIOV1 is connected to + * a 1.8v and a 3.3v power load switch that providing signal voltage to + * sdhci0 bus. + * If GPIOV0 is active high, sdhci0 is enabled, otherwise, sdhci0 is disabled. + * If GPIOV1 is active high, 3.3v power load switch is enabled, sdhci0 signal + * voltage is 3.3v, otherwise, 1.8v power load switch will be enabled, + * sdhci0 signal voltage becomes 1.8v. + * AST2600-A2 EVB also support toggling signal voltage for sdhci1. + * The design is the same as sdhci0, it uses GPIOV2 as power-gpio and GPIOV3 + * as power-switch-gpio. + */ &emmc { non-removable; bus-width = <4>; -- 2.17.1