diff options
Diffstat (limited to 'drivers/char/adc-ns9215.c')
| -rw-r--r-- | drivers/char/adc-ns9215.c | 257 |
1 files changed, 257 insertions, 0 deletions
diff --git a/drivers/char/adc-ns9215.c b/drivers/char/adc-ns9215.c new file mode 100644 index 000000000000..3c2b12c39f4d --- /dev/null +++ b/drivers/char/adc-ns9215.c @@ -0,0 +1,257 @@ +/* + * linux/drivers/char/adc-ns9215.c + * + * Copyright (C) 2008 by Digi International Inc. + * All rights reserved. + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 as published by + * the Free Software Foundation. + */ + +#include <linux/cdev.h> +#include <linux/clk.h> +#include <linux/fs.h> +#include <linux/init.h> +#include <linux/io.h> +#include <linux/module.h> +#include <linux/platform_device.h> +#include <linux/uaccess.h> + +/* registers */ +#define ADC_CONFIG (0x0) +#define ADC_CLOCK (0x4) +#define ADC_OUTPUT (0x8) +#define ADC_OUTPUT_OFFS (0x4) + +/* configuration bit fields */ +#define ADC_CONFIG_DISABLE (0 << 31) +#define ADC_CONFIG_ENABLE (1 << 31) +#define ADC_CONFIG_ENABLECHANNELS (7) + +#define DRIVER_NAME "adc-ns9215" +#define CHANNELS 8 +#define MAXCLOCK 14000000 /* max 14MHz */ +#define MAXCLOCKN 0x3FF + +struct ns9215_adc_channel { + struct semaphore sem; + int pos; + unsigned char lb; +}; + +struct ns9215_adc_pdata { + void __iomem *ioaddr; + struct resource *mem; + struct clk *clk; + struct cdev cdev; + struct ns9215_adc_channel channel[CHANNELS]; + dev_t dev_id; +}; + +static struct ns9215_adc_pdata pdata; + +ssize_t ns9215_adc_read(struct file *filep, char __user *buff, + size_t count, loff_t *offp) +{ + unsigned int val; + unsigned char buf[2]; + int channel = (int)filep->private_data; + + if (pdata.channel[channel].pos == 1) { + copy_to_user(buff, &pdata.channel[channel].lb, 1); + pdata.channel[channel].pos = 0; + return 1; + } + + val = ioread32(pdata.ioaddr + ADC_OUTPUT + (channel * ADC_OUTPUT_OFFS)); + buf[1] = (val & 0xf00) >> 8; + buf[0] = val & 0xff; + + if (count == 1) { + copy_to_user(buff, buf , 1); + pdata.channel[channel].pos = 1; + pdata.channel[channel].lb = buf[1]; + return 1; + } + + copy_to_user(buff, buf, 2); + return 2; +} + +int ns9215_adc_open(struct inode *inode, struct file *filep) +{ + int channel = iminor(inode); + + if (down_trylock(&pdata.channel[channel].sem) < 0) + return -EBUSY; + + filep->private_data = (void *)channel; + pdata.channel[channel].pos = 0; + + return 0; +} + +int ns9215_adc_release(struct inode *inode, struct file *filep) +{ + int channel = iminor(inode); + + up(&pdata.channel[channel].sem); + + return 0; +} + +struct file_operations ns9215_adc_fops = { + .owner = THIS_MODULE, + .read = ns9215_adc_read, + .open = ns9215_adc_open, + .release = ns9215_adc_release, +}; + +static int __init ns9215_adc_probe(struct platform_device *pdev) +{ + int i, ret; + unsigned int clockn; + + pdata.mem = platform_get_resource(pdev, IORESOURCE_MEM, 0); + if (!pdata.mem) { + pr_err(DRIVER_NAME ": memory not available\n"); + return -ENOENT; + } + + if (!request_mem_region(pdata.mem->start, + pdata.mem->end - pdata.mem->start + 1, + DRIVER_NAME)) { + pr_err(DRIVER_NAME ": memory already mapped\n"); + goto ns9215_err_mem; + } + + pdata.ioaddr = ioremap(pdata.mem->start, + pdata.mem->end - pdata.mem->start + 1); + if (pdata.ioaddr <= 0) { + pr_err(DRIVER_NAME ": unable to remap IO memory\n"); + goto ns9215_err_remap; + } + pr_debug(DRIVER_NAME ": mapped ADC to virtual address 0x%x\n", + (int)pdata.ioaddr); + + if (alloc_chrdev_region(&pdata.dev_id, 0, CHANNELS, DRIVER_NAME) < 0) { + pr_err(DRIVER_NAME ": requesting chrdev_region fails\n"); + goto ns9215_err_cdev_reg; + } + + pdata.clk = clk_get(&pdev->dev, DRIVER_NAME); + if (IS_ERR(pdata.clk)) { + ret = PTR_ERR(pdata.clk); + goto ns9215_err_clk_get; + } + + ret = clk_enable(pdata.clk); + if (ret) { + pr_err(DRIVER_NAME ": cannot enable clock\n"); + goto ns9215_err_clk_enable; + } + + /* set clock */ + clockn = ((clk_get_rate(pdata.clk)) - 2 * MAXCLOCK) + / (2 * MAXCLOCK) + 1; + if (clockn > MAXCLOCKN) { + pr_warning(DRIVER_NAME ": cannot set a proper ADC clock," + " ADC will not work correctly!\n"); + clockn = MAXCLOCKN; + } + + iowrite32(clockn, pdata.ioaddr + ADC_CLOCK); + + /* initialize mutexes for every channel */ + for (i = 0; i < CHANNELS; i++) { + init_MUTEX(&pdata.channel[i].sem); + pdata.channel[i].pos = 0; + } + + /* enable adc & all channels */ + iowrite32(ADC_CONFIG_ENABLE | ADC_CONFIG_ENABLECHANNELS, + pdata.ioaddr + ADC_CONFIG); + + cdev_init(&pdata.cdev, &ns9215_adc_fops); + if (cdev_add(&pdata.cdev, pdata.dev_id, CHANNELS) < 0) { + pr_err(DRIVER_NAME ": cannot add character device\n"); + goto ns9215_err_cdev_add; + } + + pr_info(DRIVER_NAME ": ADC available on MAJOR %i\n", + MAJOR(pdata.dev_id)); + + return 0; + +ns9215_err_cdev_add: + clk_disable(pdata.clk); +ns9215_err_clk_enable: + clk_put(pdata.clk); +ns9215_err_clk_get: + unregister_chrdev_region(pdata.dev_id, CHANNELS); +ns9215_err_cdev_reg: + iounmap(pdata.ioaddr); +ns9215_err_remap: + release_mem_region(pdata.mem->start, + pdata.mem->end - pdata.mem->start + 1); +ns9215_err_mem: + + return -EIO; +} + +static int ns9215_adc_remove(struct platform_device *pdev) +{ + int i; + + /* lock/check all channels */ + for (i = 0; i < CHANNELS; i++) + if (down_trylock(&pdata.channel[i].sem)) + /* channel still locked! */ + goto ns9215_adc_remove_unlock; + + /* disable ADC */ + iowrite32(ADC_CONFIG_DISABLE, pdata.ioaddr + ADC_CONFIG); + + cdev_del(&pdata.cdev); + clk_disable(pdata.clk); + clk_put(pdata.clk); + unregister_chrdev_region(pdata.dev_id, CHANNELS); + iounmap(pdata.ioaddr); + release_mem_region(pdata.mem->start, + pdata.mem->end - pdata.mem->start + 1); + + return 0; + +ns9215_adc_remove_unlock: + for (i--; i >= 0; i--) + up(&pdata.channel[i].sem); + return -EBUSY; +} + +static struct platform_driver ns9215_adc_driver = { + .probe = ns9215_adc_probe, + .remove = ns9215_adc_remove, + .driver = { + .name = DRIVER_NAME, + .owner = THIS_MODULE, + }, + /* TODO: power management */ +}; + +static int __init ns9215_adc_init(void) +{ + return platform_driver_register(&ns9215_adc_driver); +} + +static void __exit ns9215_adc_exit(void) +{ + platform_driver_unregister(&ns9215_adc_driver); +} + +module_init(ns9215_adc_init); +module_exit(ns9215_adc_exit); + +MODULE_AUTHOR("Matthias Ludwig"); +MODULE_DESCRIPTION("ADC driver for Digi NS9215"); +MODULE_LICENSE("GPL v2"); |