Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755837AbbFORdU (ORCPT ); Mon, 15 Jun 2015 13:33:20 -0400 Received: from down.free-electrons.com ([37.187.137.238]:42943 "EHLO mail.free-electrons.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750917AbbFORdF (ORCPT ); Mon, 15 Jun 2015 13:33:05 -0400 Date: Mon, 15 Jun 2015 19:32:57 +0200 From: Boris Brezillon To: Cyrille Pitchen Cc: , , , , , , , , , , , Subject: Re: [PATCH linux-next 2/2] mfd: flexcom: add a driver for Atmel Flexible Serial Communication Unit Message-ID: <20150615193257.42c9df3d@bbrezillon> In-Reply-To: References: X-Mailer: Claws Mail 3.9.3 (GTK+ 2.24.23; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5099 Lines: 155 On Mon, 15 Jun 2015 18:38:05 +0200 Cyrille Pitchen wrote: > This driver supports the new Atmel Flexcom. The Flexcom is a wrapper which > integrates one SPI controller, one I2C controller and one USART. Only one > function can be enabled at a time. This driver selects the function once > for all, when the Flexcom is probed, according to the value of the new > "atmel,flexcom-mode" device tree property. > > This driver has chosen to present the Flexcom to the system as a MFD so > the implementation is seamless for the existing Atmel SPI, I2C and USART > drivers. > > Also the Flexcom embeds FIFOs: the latest patches of the SPI, I2C and > USART drivers take advantage of this new feature. > > Signed-off-by: Cyrille Pitchen > --- > drivers/mfd/Kconfig | 11 +++++ > drivers/mfd/Makefile | 1 + > drivers/mfd/atmel-flexcom.c | 97 +++++++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 109 insertions(+) > create mode 100644 drivers/mfd/atmel-flexcom.c > > diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig > index aefbbbf..4aebf08 100644 > --- a/drivers/mfd/Kconfig > +++ b/drivers/mfd/Kconfig > @@ -60,6 +60,17 @@ config MFD_AAT2870_CORE > additional drivers must be enabled in order to use the > functionality of the device. > > +config MFD_ATMEL_FLEXCOM > + tristate "Atmel Flexcom (Flexible Serial Communication Unit)" > + select MFD_CORE > + depends on OF > + help > + Select this to get support for Atmel Flexcom. This is a wrapper > + which embeds a SPI controller, a I2C controller and a USART. Only > + one function can be used at a time. The choice is done at boot time > + by the probe function of this MFD driver according to a device tree > + property. > + > config MFD_ATMEL_HLCDC > tristate "Atmel HLCDC (High-end LCD Controller)" > select MFD_CORE > diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile > index ea40e07..0705eb2 100644 > --- a/drivers/mfd/Makefile > +++ b/drivers/mfd/Makefile > @@ -160,6 +160,7 @@ obj-$(CONFIG_MFD_SPMI_PMIC) += qcom-spmi-pmic.o > obj-$(CONFIG_TPS65911_COMPARATOR) += tps65911-comparator.o > obj-$(CONFIG_MFD_TPS65090) += tps65090.o > obj-$(CONFIG_MFD_AAT2870_CORE) += aat2870-core.o > +obj-$(CONFIG_MFD_ATMEL_FLEXCOM) += atmel-flexcom.o > obj-$(CONFIG_MFD_ATMEL_HLCDC) += atmel-hlcdc.o > obj-$(CONFIG_MFD_INTEL_MSIC) += intel_msic.o > obj-$(CONFIG_MFD_PALMAS) += palmas.o > diff --git a/drivers/mfd/atmel-flexcom.c b/drivers/mfd/atmel-flexcom.c > new file mode 100644 > index 0000000..14c35e6 > --- /dev/null > +++ b/drivers/mfd/atmel-flexcom.c > @@ -0,0 +1,97 @@ > +/* > + * Driver for Atmel Flexcom > + * > + * Copyright (C) 2015 Atmel Corporation > + * > + * Author: Cyrille Pitchen > + * > + * This program is free software; you can redistribute it and/or modify > + * it under the terms of the GNU General Public License as published by > + * the Free Software Foundation; either version 2 of the License, or > + * (at your option) any later version. > + * > + */ > + > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > + > +#define FX_MR 0x0 > +#define FX_RHR 0x10 > +#define FX_THR 0x20 > +#define FX_VERSION 0xfc > + > +#define FX_MR_NO_COM 0 > +#define FX_MR_USART 1 > +#define FX_MR_SPI 2 > +#define FX_MR_TWI 3 > + > + > +static int atmel_flexcom_probe(struct platform_device *pdev) > +{ > + struct clk *clk; > + struct resource *res; > + unsigned char __iomem *map; > + unsigned int version, mr; > + const char *mode; > + int err; > + > + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); > + map = devm_ioremap_resource(&pdev->dev, res); If you take the approach I suggested in the DT binding review, you shouldn't reserve the whole memory region, just the flexcom part(0x0 to 0x200). > + if (IS_ERR(map)) > + return PTR_ERR(map); > + > + clk = devm_clk_get(&pdev->dev, NULL); > + if (IS_ERR(clk)) > + return PTR_ERR(clk); > + > + err = of_property_read_string(pdev->dev.of_node, > + "atmel,flexcom-mode", &mode); > + if (err) > + return err; > + > + if (!strcmp(mode, "usart")) > + mr = FX_MR_USART; > + else if (!strcmp(mode, "spi")) > + mr = FX_MR_SPI; > + else if (!strcmp(mode, "twi") || !strcmp(mode, "i2c")) > + mr = FX_MR_TWI; > + else > + return -EINVAL; > + > + clk_prepare_enable(clk); > + version = __raw_readl(map + FX_VERSION); > + __raw_writel(mr, map + FX_MR); > + clk_disable_unprepare(clk); Is there a good reason to use the __raw versions of the writel/readl functions ? -- Boris Brezillon, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/