From patchwork Mon Jul 30 00:30:26 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: NeilBrown X-Patchwork-Id: 1253111 Return-Path: X-Original-To: patchwork-linux-omap@patchwork.kernel.org Delivered-To: patchwork-process-083081@patchwork1.kernel.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by patchwork1.kernel.org (Postfix) with ESMTP id E94463FCFC for ; Mon, 30 Jul 2012 00:31:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753805Ab2G3Aas (ORCPT ); Sun, 29 Jul 2012 20:30:48 -0400 Received: from cantor2.suse.de ([195.135.220.15]:42378 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753685Ab2G3Aaq (ORCPT ); Sun, 29 Jul 2012 20:30:46 -0400 Received: from relay1.suse.de (unknown [195.135.220.254]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mx2.suse.de (Postfix) with ESMTP id 99BEB98E46; Mon, 30 Jul 2012 02:30:44 +0200 (CEST) Date: Mon, 30 Jul 2012 10:30:26 +1000 From: NeilBrown To: linux-serial@vger.kernel.org, linux-omap@vger.kernel.org, linux-kernel@vger.kernel.org, Tony Lindgren , Alan Cox , Greg Kroah-Hartman Cc: "Govindraj.R" , Kevin Hilman , "H. Peter Anvin" Subject: [PATCH] OMAP/serial: Add support for driving a GPIO as DTR. Message-ID: <20120730103026.6b17f9e2@notabene.brown> X-Mailer: Claws Mail 3.7.10 (GTK+ 2.24.7; x86_64-suse-linux-gnu) Mime-Version: 1.0 Sender: linux-omap-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-omap@vger.kernel.org Hi all, this is my current patch which answers my question from May: Question: How to power-manage UART-attached devices. It teaches omap2/serial about the possibility of a GPIO which is to be driven as a DTR line. This allows me to power on/off devices that are accessed via a serial port (GPS, Bluetooth) when the port is opened/closed. I simply write a driver which exports a GPIO line and does the required magic when it is driven high or low. - because '0' is a valid GPIO number, I added an extra port_info field call 'DTR_present' so existing code wouldn't accidentally request to use GPIO-0 as a DTR - is there a better way to handle this? - I added a DTR_inverted field so you could choose the polarity of the GPIO line ... I'm not really sure this is needed so I'll probably drop it unless encouraged otherwise. - If the gpio 'can_sleep', then I need a work-queue to effect the change, and I currently use the 'qos_work' rather than adding another work handler. As both the qos_work and the gpio work tasks are idempotent and rare, this seems reasonable. Is it OK? should I make another work_struct? or something else? Thanks, NeilBrown --------------------- OMAP hardware doesn't provide a phyisical DTR line, but some configurations may need a DTR line which tracks whether the device is open or not. So allow a gpio to be configured as the DTR line. Signed-off-by: NeilBrown diff --git a/arch/arm/mach-omap2/serial.c b/arch/arm/mach-omap2/serial.c index c1b93c7..25d53b2 100644 --- a/arch/arm/mach-omap2/serial.c +++ b/arch/arm/mach-omap2/serial.c @@ -304,6 +304,9 @@ void __init omap_serial_init_port(struct omap_board_data *bdata, omap_up.dma_rx_timeout = info->dma_rx_timeout; omap_up.dma_rx_poll_rate = info->dma_rx_poll_rate; omap_up.autosuspend_timeout = info->autosuspend_timeout; + omap_up.DTR_gpio = info->DTR_gpio; + omap_up.DTR_inverted = info->DTR_inverted; + omap_up.DTR_present = info->DTR_present; pdata = &omap_up; pdata_size = sizeof(struct omap_uart_port_info); diff --git a/arch/arm/plat-omap/include/plat/omap-serial.h b/arch/arm/plat-omap/include/plat/omap-serial.h index 1a52725..52d3de4 100644 --- a/arch/arm/plat-omap/include/plat/omap-serial.h +++ b/arch/arm/plat-omap/include/plat/omap-serial.h @@ -69,6 +69,9 @@ struct omap_uart_port_info { unsigned int dma_rx_timeout; unsigned int autosuspend_timeout; unsigned int dma_rx_poll_rate; + int DTR_gpio; + int DTR_inverted; + int DTR_present; int (*get_context_loss_count)(struct device *); void (*set_forceidle)(struct platform_device *); @@ -131,6 +134,10 @@ struct uart_omap_port { u32 errata; u8 wakeups_enabled; + int DTR_gpio; + int DTR_inverted; + int DTR_active; + struct pm_qos_request pm_qos_request; u32 latency; u32 calc_latency; diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c index d3cda0c..aa603f2 100644 --- a/drivers/tty/serial/omap-serial.c +++ b/drivers/tty/serial/omap-serial.c @@ -39,6 +39,7 @@ #include #include #include +#include #include #include @@ -507,6 +508,16 @@ static void serial_omap_set_mctrl(struct uart_port *port, unsigned int mctrl) up->mcr |= mcr; serial_out(up, UART_MCR, up->mcr); pm_runtime_put(&up->pdev->dev); + + if (gpio_is_valid(up->DTR_gpio) && + !!(mctrl & TIOCM_DTR) != up->DTR_active) { + up->DTR_active = !up->DTR_active; + if (gpio_cansleep(up->DTR_gpio)) + schedule_work(&up->qos_work); + else + gpio_set_value(up->DTR_gpio, + up->DTR_active != up->DTR_inverted); + } } static void serial_omap_break_ctl(struct uart_port *port, int break_state) @@ -715,6 +726,9 @@ static void serial_omap_uart_qos_work(struct work_struct *work) qos_work); pm_qos_update_request(&up->pm_qos_request, up->latency); + if (gpio_is_valid(up->DTR_gpio)) + gpio_set_value_cansleep(up->DTR_gpio, + up->DTR_active != up->DTR_inverted); } static void @@ -1435,7 +1449,7 @@ static int serial_omap_probe(struct platform_device *pdev) struct uart_omap_port *up; struct resource *mem, *irq, *dma_tx, *dma_rx; struct omap_uart_port_info *omap_up_info = pdev->dev.platform_data; - int ret = -ENOSPC; + int ret; if (pdev->dev.of_node) omap_up_info = of_get_uart_port_info(&pdev->dev); @@ -1466,10 +1480,29 @@ static int serial_omap_probe(struct platform_device *pdev) if (!dma_tx) return -ENXIO; + if (gpio_is_valid(omap_up_info->DTR_gpio) && + omap_up_info->DTR_present) { + ret = gpio_request(omap_up_info->DTR_gpio, "omap-serial"); + if (ret < 0) + return ret; + ret = gpio_direction_output(omap_up_info->DTR_gpio, + omap_up_info->DTR_inverted); + if (ret < 0) + return ret; + } + up = devm_kzalloc(&pdev->dev, sizeof(*up), GFP_KERNEL); if (!up) return -ENOMEM; + if (gpio_is_valid(omap_up_info->DTR_gpio) && + omap_up_info->DTR_present) { + up->DTR_gpio = omap_up_info->DTR_gpio; + up->DTR_inverted = omap_up_info->DTR_inverted; + } else + up->DTR_gpio = -EINVAL; + up->DTR_active = 0; + up->pdev = pdev; up->port.dev = &pdev->dev; up->port.type = PORT_OMAP;