Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757789Ab3EJRcE (ORCPT ); Fri, 10 May 2013 13:32:04 -0400 Received: from mail-da0-f43.google.com ([209.85.210.43]:63533 "EHLO mail-da0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757538Ab3EJRcA (ORCPT ); Fri, 10 May 2013 13:32:00 -0400 From: Soren Brinkmann To: Mike Turquette Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Soren Brinkmann Subject: [PATCH RFC] clk: Introduce userspace clock driver Date: Fri, 10 May 2013 10:31:31 -0700 Message-Id: <1368207091-32538-2-git-send-email-soren.brinkmann@xilinx.com> X-Mailer: git-send-email 1.8.2.3 In-Reply-To: <1368207091-32538-1-git-send-email-soren.brinkmann@xilinx.com> References: <1368207091-32538-1-git-send-email-soren.brinkmann@xilinx.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6706 Lines: 241 The userspace clock driver can be used to expose clock controls through sysfs to userspace. The driver creates entries in /sys/class/clk. Signed-off-by: Soren Brinkmann --- .../devicetree/bindings/clock/clk-userspace.txt | 7 + drivers/clk/Kconfig | 9 ++ drivers/clk/Makefile | 1 + drivers/clk/clk-userspace.c | 169 +++++++++++++++++++++ 4 files changed, 186 insertions(+) create mode 100644 Documentation/devicetree/bindings/clock/clk-userspace.txt create mode 100644 drivers/clk/clk-userspace.c diff --git a/Documentation/devicetree/bindings/clock/clk-userspace.txt b/Documentation/devicetree/bindings/clock/clk-userspace.txt new file mode 100644 index 0000000..2d153c7 --- /dev/null +++ b/Documentation/devicetree/bindings/clock/clk-userspace.txt @@ -0,0 +1,7 @@ + +Example: + usclk: usclk { + compatible = "clk-userspace"; + clocks = <&foo 15>, <&bar>; + clock-count = <2>; + }; diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig index 0357ac4..b35b62c 100644 --- a/drivers/clk/Kconfig +++ b/drivers/clk/Kconfig @@ -81,6 +81,15 @@ config COMMON_CLK_AXI_CLKGEN Support for the Analog Devices axi-clkgen pcore clock generator for Xilinx FPGAs. It is commonly used in Analog Devices' reference designs. +config COMMON_CLK_USERSPACE + bool "Userspace Clock Controls" + depends on OF + depends on SYSFS + help + ---help--- + Expose clock controls through sysfs to userspace. Clocks are selected + through the device tree and the controls are exposed in + /sys/class/clk. endmenu source "drivers/clk/mvebu/Kconfig" diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile index fa435bc..f2f68c8 100644 --- a/drivers/clk/Makefile +++ b/drivers/clk/Makefile @@ -8,6 +8,7 @@ obj-$(CONFIG_COMMON_CLK) += clk-fixed-rate.o obj-$(CONFIG_COMMON_CLK) += clk-gate.o obj-$(CONFIG_COMMON_CLK) += clk-mux.o obj-$(CONFIG_COMMON_CLK) += clk-composite.o +obj-$(CONFIG_COMMON_CLK_USERSPACE) += clk-userspace.o # SoCs specific obj-$(CONFIG_ARCH_BCM2835) += clk-bcm2835.o diff --git a/drivers/clk/clk-userspace.c b/drivers/clk/clk-userspace.c new file mode 100644 index 0000000..931cf92 --- /dev/null +++ b/drivers/clk/clk-userspace.c @@ -0,0 +1,169 @@ +/* + * Userspace clock driver + * + * Copyright (C) 2013 Xilinx + * + * Sören Brinkmann + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License v2 as published by + * the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see . + * + * Expose clock controls through sysfs to userspace. + * + * By writing 0/1 to 'enable' the clock can be disabled/enabled. Reading + * that file returns the current state - 0 = disabled, 1 = enabled. + * + * Reading 'set_rate' returns the current clock frequency in Hz. Writing + * the file requests setting a new frequency in Hz. + */ + +#include +#include +#include +#include +#include +#include + +#define DRIVER_NAME "clk-userspace" + +struct usclk_data { + struct clk *clk; + int enabled; +}; + +static ssize_t enable_show(struct device *dev, struct device_attribute *attr, + char *buf) +{ + struct usclk_data *pdata = dev_get_drvdata(dev); + + return scnprintf(buf, PAGE_SIZE, "%u\n", pdata->enabled); +} + +static ssize_t enable_store(struct device *dev, struct device_attribute *attr, + const char *buf, size_t count) +{ + unsigned long enable; + int ret; + struct usclk_data *pdata = dev_get_drvdata(dev); + + ret = kstrtoul(buf, 0, &enable); + if (ret) + return -EINVAL; + + enable = !!enable; + if (enable == pdata->enabled) + return count; + + if (enable) + ret = clk_prepare_enable(pdata->clk); + else + clk_disable_unprepare(pdata->clk); + + if (ret) + return -EBUSY; + + pdata->enabled = enable; + return count; +} + +static DEVICE_ATTR(enable, 0644, enable_show, enable_store); + +static ssize_t set_rate_show(struct device *dev, struct device_attribute *attr, + char *buf) +{ + struct usclk_data *pdata = dev_get_drvdata(dev); + + return scnprintf(buf, PAGE_SIZE, "%lu\n", clk_get_rate(pdata->clk)); +} + +static ssize_t set_rate_store(struct device *dev, struct device_attribute *attr, + const char *buf, size_t count) +{ + int ret = 0; + unsigned long rate; + struct usclk_data *pdata = dev_get_drvdata(dev); + + ret = kstrtoul(buf, 0, &rate); + if (ret) + return -EINVAL; + + rate = clk_round_rate(pdata->clk, rate); + ret = clk_set_rate(pdata->clk, rate); + if (ret) + return -EBUSY; + + return count; +} + +static DEVICE_ATTR(set_rate, 0644, set_rate_show, set_rate_store); + +static const struct attribute *usclk_attrs[] = { + &dev_attr_enable.attr, + &dev_attr_set_rate.attr, + NULL +}; + +static const struct attribute_group usclk_attr_grp = { + .attrs = (struct attribute **)usclk_attrs, +}; + +static int usclk_setup(void) +{ + int ret; + int i; + struct usclk_data *pdata; + u32 clock_count; + struct class *clk_class; + struct device *dev; + struct device_node *np = of_find_compatible_node(NULL, NULL, + "clk-userspace"); + + ret = of_property_read_u32(np, "clock-count", &clock_count); + if (ret || !clock_count) + return ret; + + pdata = kzalloc(clock_count * sizeof(*pdata), GFP_KERNEL); + if (!pdata) + return -ENOMEM; + + clk_class = class_create(THIS_MODULE, "clk"); + if (!clk_class) { + pr_err("unable to create class\n"); + goto err_free; + } + + for (i = 0; i < clock_count; i++) { + pdata[i].clk = of_clk_get(np, i); + if (IS_ERR(pdata[i].clk)) { + pr_warn("input clock #%u not found\n", i); + continue; + } + + dev = device_create(clk_class, NULL, MKDEV(0, 0), NULL, + of_clk_get_parent_name(np, i)); + if (!dev) { + pr_warn("unable to create device #%d\n", i); + continue; + } + + dev_set_drvdata(dev, &pdata[i]); + sysfs_create_group(&dev->kobj, &usclk_attr_grp); + } + + return 0; + +err_free: + kfree(pdata); + + return ret; +} +late_initcall(usclk_setup); -- 1.8.2.3 -- 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/