From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753207AbbKYWDA (ORCPT ); Wed, 25 Nov 2015 17:03:00 -0500 Received: from mail.savoirfairelinux.com ([208.88.110.44]:33002 "EHLO mail.savoirfairelinux.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753151AbbKYWCo (ORCPT ); Wed, 25 Nov 2015 17:02:44 -0500 Date: Wed, 25 Nov 2015 17:02:39 -0500 From: Damien Riegel To: Rob Herring Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-watchdog@vger.kernel.org, devicetree@vger.kernel.org, Lee Jones , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , Russell King , Shawn Guo , Sascha Hauer , Arnd Bergmann , Samuel Ortiz , Wim Van Sebroeck , Guenter Roeck , kernel@savoirfairelinux.com Subject: Re: [PATCH v6 2/6] mfd: syscon: add a DT property to set value width Message-ID: <20151125220239.GB3627@localhost> Mail-Followup-To: Damien Riegel , Rob Herring , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-watchdog@vger.kernel.org, devicetree@vger.kernel.org, Lee Jones , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , Russell King , Shawn Guo , Sascha Hauer , Arnd Bergmann , Samuel Ortiz , Wim Van Sebroeck , Guenter Roeck , kernel@savoirfairelinux.com References: <1448479507-1951-1-git-send-email-damien.riegel@savoirfairelinux.com> <1448479507-1951-3-git-send-email-damien.riegel@savoirfairelinux.com> <20151125203253.GA13437@rob-hp-laptop> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20151125203253.GA13437@rob-hp-laptop> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 25, 2015 at 02:32:53PM -0600, Rob Herring wrote: > On Wed, Nov 25, 2015 at 02:25:03PM -0500, Damien Riegel wrote: > > Currently syscon has a fixed configuration of 32 bits for register and > > values widths. In some cases, it would be desirable to be able to > > customize the value width. > > > > For example, certain boards (like the ones manufactured by Technologic > > Systems) have a FPGA that is memory-mapped, but its registers are only > > 16-bit wide. > > > > This patch adds an optional "bus-width" DT binding for syscon that > > allows to change the width for the data bus (i.e. val_bits). If this > > property is provided, it will also adjust the register stride to > > bus-width / 8. If not provided, the default configuration is used. > > See the 8250 UART bindings. This problem is already solved and has > standard bindings for it. Okay, I'll change bus-width to reg-io-width. Are you also suggesting to use reg-shift to parametrize reg_stride? > Rob > > > > > Signed-off-by: Damien Riegel > > Acked-by: Arnd Bergmann > > Acked-by: Lee Jones > > --- > > Documentation/devicetree/bindings/mfd/syscon.txt | 3 +++ > > drivers/mfd/syscon.c | 13 +++++++++++++ > > 2 files changed, 16 insertions(+) > > > > diff --git a/Documentation/devicetree/bindings/mfd/syscon.txt b/Documentation/devicetree/bindings/mfd/syscon.txt > > index fe8150b..4c9d187 100644 > > --- a/Documentation/devicetree/bindings/mfd/syscon.txt > > +++ b/Documentation/devicetree/bindings/mfd/syscon.txt > > @@ -13,6 +13,9 @@ Required properties: > > - compatible: Should contain "syscon". > > - reg: the register region can be accessed from syscon > > > > +Optional property: > > +- bus-width: width of the data bus. Can be <8>, <16>, <32>, or <64>. > > + > > Examples: > > gpr: iomuxc-gpr@020e0000 { > > compatible = "fsl,imx6q-iomuxc-gpr", "syscon"; > > diff --git a/drivers/mfd/syscon.c b/drivers/mfd/syscon.c > > index 176bf0f..5a93d80 100644 > > --- a/drivers/mfd/syscon.c > > +++ b/drivers/mfd/syscon.c > > @@ -47,6 +47,7 @@ static struct syscon *of_syscon_register(struct device_node *np) > > struct syscon *syscon; > > struct regmap *regmap; > > void __iomem *base; > > + u32 bus_width; > > int ret; > > struct regmap_config syscon_config = syscon_regmap_config; > > > > @@ -69,6 +70,18 @@ static struct syscon *of_syscon_register(struct device_node *np) > > else if (of_property_read_bool(np, "little-endian")) > > syscon_config.val_format_endian = REGMAP_ENDIAN_LITTLE; > > > > + /* > > + * search for bus-width property in DT. If it is not provided, default > > + * to 32-bit. regmap_init_mmio will return an error if syscon_config's > > + * values are invalid so there is no need to check them here. > > + */ > > + ret = of_property_read_u32(np, "bus-width", &bus_width); > > + if (ret) > > + bus_width = 32; > > + > > + syscon_config.val_bits = bus_width; > > + syscon_config.reg_stride = syscon_config.val_bits / 8; > > + > > regmap = regmap_init_mmio(NULL, base, &syscon_config); > > if (IS_ERR(regmap)) { > > pr_err("regmap init failed\n"); > > -- > > 2.5.0 > > From mboxrd@z Thu Jan 1 00:00:00 1970 From: damien.riegel@savoirfairelinux.com (Damien Riegel) Date: Wed, 25 Nov 2015 17:02:39 -0500 Subject: [PATCH v6 2/6] mfd: syscon: add a DT property to set value width In-Reply-To: <20151125203253.GA13437@rob-hp-laptop> References: <1448479507-1951-1-git-send-email-damien.riegel@savoirfairelinux.com> <1448479507-1951-3-git-send-email-damien.riegel@savoirfairelinux.com> <20151125203253.GA13437@rob-hp-laptop> Message-ID: <20151125220239.GB3627@localhost> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Wed, Nov 25, 2015 at 02:32:53PM -0600, Rob Herring wrote: > On Wed, Nov 25, 2015 at 02:25:03PM -0500, Damien Riegel wrote: > > Currently syscon has a fixed configuration of 32 bits for register and > > values widths. In some cases, it would be desirable to be able to > > customize the value width. > > > > For example, certain boards (like the ones manufactured by Technologic > > Systems) have a FPGA that is memory-mapped, but its registers are only > > 16-bit wide. > > > > This patch adds an optional "bus-width" DT binding for syscon that > > allows to change the width for the data bus (i.e. val_bits). If this > > property is provided, it will also adjust the register stride to > > bus-width / 8. If not provided, the default configuration is used. > > See the 8250 UART bindings. This problem is already solved and has > standard bindings for it. Okay, I'll change bus-width to reg-io-width. Are you also suggesting to use reg-shift to parametrize reg_stride? > Rob > > > > > Signed-off-by: Damien Riegel > > Acked-by: Arnd Bergmann > > Acked-by: Lee Jones > > --- > > Documentation/devicetree/bindings/mfd/syscon.txt | 3 +++ > > drivers/mfd/syscon.c | 13 +++++++++++++ > > 2 files changed, 16 insertions(+) > > > > diff --git a/Documentation/devicetree/bindings/mfd/syscon.txt b/Documentation/devicetree/bindings/mfd/syscon.txt > > index fe8150b..4c9d187 100644 > > --- a/Documentation/devicetree/bindings/mfd/syscon.txt > > +++ b/Documentation/devicetree/bindings/mfd/syscon.txt > > @@ -13,6 +13,9 @@ Required properties: > > - compatible: Should contain "syscon". > > - reg: the register region can be accessed from syscon > > > > +Optional property: > > +- bus-width: width of the data bus. Can be <8>, <16>, <32>, or <64>. > > + > > Examples: > > gpr: iomuxc-gpr at 020e0000 { > > compatible = "fsl,imx6q-iomuxc-gpr", "syscon"; > > diff --git a/drivers/mfd/syscon.c b/drivers/mfd/syscon.c > > index 176bf0f..5a93d80 100644 > > --- a/drivers/mfd/syscon.c > > +++ b/drivers/mfd/syscon.c > > @@ -47,6 +47,7 @@ static struct syscon *of_syscon_register(struct device_node *np) > > struct syscon *syscon; > > struct regmap *regmap; > > void __iomem *base; > > + u32 bus_width; > > int ret; > > struct regmap_config syscon_config = syscon_regmap_config; > > > > @@ -69,6 +70,18 @@ static struct syscon *of_syscon_register(struct device_node *np) > > else if (of_property_read_bool(np, "little-endian")) > > syscon_config.val_format_endian = REGMAP_ENDIAN_LITTLE; > > > > + /* > > + * search for bus-width property in DT. If it is not provided, default > > + * to 32-bit. regmap_init_mmio will return an error if syscon_config's > > + * values are invalid so there is no need to check them here. > > + */ > > + ret = of_property_read_u32(np, "bus-width", &bus_width); > > + if (ret) > > + bus_width = 32; > > + > > + syscon_config.val_bits = bus_width; > > + syscon_config.reg_stride = syscon_config.val_bits / 8; > > + > > regmap = regmap_init_mmio(NULL, base, &syscon_config); > > if (IS_ERR(regmap)) { > > pr_err("regmap init failed\n"); > > -- > > 2.5.0 > >