/* * Driver for ADC on the FoxBoardG20 * * Copyright (R) 2010 - Claudio Mignanti * Based on http://www.at91.com/forum/viewtopic.php/p,9409/#p9409 * * Copyright (C) 2010 Stefano Barbato - stefano@codesink.org * * 2010/05/18 Antonio Galea * Sysfs device model, different drivers integration * * WISHLIST: * - concurrent access control * - add support for dynamic reconfiguration * - hardware triggers * * 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. * * $Id$ * --------------------------------------------------------------------------- */ #include #include #include #include #include #include #include #include #include #include #include "at91_adc.h" #if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,37) #define USE_UNLOCKED_IOCTL #endif static void at91_adc_device_release(struct device *dev){} struct platform_device at91_adc_device = { .name = "at91_adc", .id = -1, .dev.release = at91_adc_device_release, }; struct clk *at91_adc_clk; void __iomem *at91_adc_base; static struct cdev *at91_adc_cdev = NULL; static dev_t at91_adc_devno = 0; static struct class *at91_adc_class = NULL; #define DRV_CLASS "at91_adc" #define ADC_READ 1 ////////////////////////////////////////////////////// // Device functions ////////////////////////////////////////////////////// #define at91_adc_read(reg) ioread32(at91_adc_base + (reg)) #define at91_adc_write(reg, val) iowrite32((val), at91_adc_base + (reg)) #define AT91_DEFAULT_CONFIG AT91_ADC_SHTIM | \ AT91_ADC_STARTUP | \ AT91_ADC_PRESCAL | \ AT91_ADC_SLEEP static int at91_adc_read_chan(int chan){ int val, sr; if(chan<0 || chan>3){ return -EINVAL; } at91_adc_write(AT91_ADC_CHER,AT91_ADC_CH(chan)); //Enable Channel at91_adc_write(AT91_ADC_CR,AT91_ADC_START); //Start the ADC for(sr=0; !(sr & AT91_ADC_EOC(chan)); sr=at91_adc_read(AT91_ADC_SR)) cpu_relax(); val=at91_adc_read(AT91_ADC_CDR(chan)) & AT91_ADC_DATA; //Read up to 10 bits return val; } static int at91_adc_config(int requested_config){ int actual_config; at91_adc_write(AT91_ADC_CR,AT91_ADC_SWRST); //Reset the ADC at91_adc_write(AT91_ADC_MR,requested_config); //Mode setup actual_config = at91_adc_read(AT91_ADC_MR); //Read it back return (requested_config==actual_config? 0: -EINVAL); } ////////////////////////////////////////////////////// // Sysfs interface ////////////////////////////////////////////////////// static ssize_t at91_adc_chanX_show( struct device *dev, struct device_attribute *attr, char *buf ){ ssize_t status = 0; int chan = -1; int value; if(strlen(attr->attr.name)==5 && strncmp(attr->attr.name,"chan",4)==0){ chan = attr->attr.name[4]-'0'; } if(chan<0 || chan>3){ return -EIO; } value = at91_adc_read_chan(chan); status = sprintf(buf, "%d\n", value); return status; } static DEVICE_ATTR(chan0, 0444, at91_adc_chanX_show, NULL); static DEVICE_ATTR(chan1, 0444, at91_adc_chanX_show, NULL); static DEVICE_ATTR(chan2, 0444, at91_adc_chanX_show, NULL); static DEVICE_ATTR(chan3, 0444, at91_adc_chanX_show, NULL); static const struct attribute *at91_adc_dev_attrs[] = { &dev_attr_chan0.attr, &dev_attr_chan1.attr, &dev_attr_chan2.attr, &dev_attr_chan3.attr, NULL, }; static const struct attribute_group at91_adc_dev_attr_group = { .attrs = (struct attribute **) at91_adc_dev_attrs, }; ////////////////////////////////////////////////////// // IOCTL interface ////////////////////////////////////////////////////// #ifdef USE_UNLOCKED_IOCTL static long at91_adc_ioctl(struct file * file, unsigned int cmd, unsigned long arg) #else static int at91_adc_ioctl(struct inode * inode, struct file * file, unsigned int cmd, unsigned long arg) #endif { int retval = 0; switch (cmd) { case ADC_READ: return at91_adc_read_chan((int)arg); break; default: retval = -EINVAL; } return retval; } struct file_operations at91_adc_fops = { .owner = THIS_MODULE, #ifdef USE_UNLOCKED_IOCTL .unlocked_ioctl = at91_adc_ioctl, #else .ioctl = at91_adc_ioctl, #endif }; static void at91_adc_cdev_teardown(void){ if(at91_adc_class){ device_destroy(at91_adc_class, at91_adc_devno); class_destroy(at91_adc_class); } if(at91_adc_devno){ unregister_chrdev_region(at91_adc_devno,1); if(at91_adc_cdev){ cdev_del(at91_adc_cdev); } } at91_adc_devno = 0; at91_adc_cdev = NULL; at91_adc_class = NULL; return; } static int at91_adc_cdev_setup(void){ int status; /* alloc a new device number (major: dynamic, minor: 0) */ status = alloc_chrdev_region(&at91_adc_devno,0,1,at91_adc_device.name); if(status){ goto err; } /* create a new char device */ at91_adc_cdev = cdev_alloc(); if(at91_adc_cdev == NULL){ status=-ENOMEM; goto err; } at91_adc_cdev->owner = THIS_MODULE; at91_adc_cdev->ops = &at91_adc_fops; status = cdev_add(at91_adc_cdev,at91_adc_devno,1); if(status){ goto err; } /* register the class */ at91_adc_class = class_create(THIS_MODULE, DRV_CLASS); if(IS_ERR(at91_adc_class)){ status=-EFAULT; goto err; } device_create(at91_adc_class, NULL, at91_adc_devno, NULL, at91_adc_device.name); printk(KERN_INFO "Major: %u; minor: %u\n", \ MAJOR(at91_adc_devno), MINOR(at91_adc_devno) \ ); return 0; err: at91_adc_cdev_teardown(); return status; } ////////////////////////////////////////////////////// // Module init/exit ////////////////////////////////////////////////////// static int __init at91_adc_init(void){ int status; at91_adc_clk = clk_get(NULL,"adc_clk"); clk_enable(at91_adc_clk); at91_adc_base = ioremap(AT91SAM9260_BASE_ADC,SZ_256); if(!at91_adc_base){ status=-ENODEV; goto fail_no_iomem; } status = platform_device_register(&at91_adc_device); if(status){ goto fail_no_dev; } status = at91_adc_config(AT91_DEFAULT_CONFIG); if(status){ goto fail_no_config; } status = sysfs_create_group( &(at91_adc_device.dev.kobj), &at91_adc_dev_attr_group ); if(status){ goto fail_no_sysfs; } status = at91_adc_cdev_setup(); if(status){ goto fail_no_cdev; } printk(KERN_INFO "Registered device at91_adc.\n"); return 0; fail_no_cdev: // nothing to undo fail_no_sysfs: // nothing to undo fail_no_config: platform_device_unregister(&at91_adc_device); fail_no_dev: iounmap(at91_adc_base); fail_no_iomem: clk_disable(at91_adc_clk); clk_put(at91_adc_clk); return status; } static void __exit at91_adc_exit(void){ at91_adc_cdev_teardown(); platform_device_unregister(&at91_adc_device); iounmap(at91_adc_base); clk_disable(at91_adc_clk); clk_put(at91_adc_clk); printk(KERN_INFO "Unregistered device at91_adc.\n"); } module_init(at91_adc_init); module_exit(at91_adc_exit); MODULE_AUTHOR("Paul Kavan"); MODULE_AUTHOR("Claudio Mignanti"); MODULE_AUTHOR("Antonio Galea"); MODULE_AUTHOR("Stefano Barbato"); MODULE_DESCRIPTION("ADC Driver for the FoxBoardG20"); MODULE_LICENSE("GPL");