diff options
| -rw-r--r-- | Documentation/spi/spidev | 307 | ||||
| -rw-r--r-- | drivers/spi/Kconfig | 9 | ||||
| -rw-r--r-- | drivers/spi/Makefile | 1 | ||||
| -rw-r--r-- | drivers/spi/spidev.c | 584 | ||||
| -rw-r--r-- | include/linux/Kbuild | 1 | ||||
| -rw-r--r-- | include/linux/spi/Kbuild | 1 | ||||
| -rw-r--r-- | include/linux/spi/spidev.h | 124 |
7 files changed, 1027 insertions, 0 deletions
diff --git a/Documentation/spi/spidev b/Documentation/spi/spidev new file mode 100644 index 000000000000..5c8e1b988a08 --- /dev/null +++ b/Documentation/spi/spidev @@ -0,0 +1,307 @@ +SPI devices have a limited userspace API, supporting basic half-duplex +read() and write() access to SPI slave devices. Using ioctl() requests, +full duplex transfers and device I/O configuration are also available. + + #include <fcntl.h> + #include <unistd.h> + #include <sys/ioctl.h> + #include <linux/types.h> + #include <linux/spi/spidev.h> + +Some reasons you might want to use this programming interface include: + + * Prototyping in an environment that's not crash-prone; stray pointers + in userspace won't normally bring down any Linux system. + + * Developing simple protocols used to talk to microcontrollers acting + as SPI slaves, which you may need to change quite often. + +Of course there are drivers that can never be written in userspace, because +they need to access kernel interfaces (such as IRQ handlers or other layers +of the driver stack) that are not accessible to userspace. + + +DEVICE CREATION, DRIVER BINDING +=============================== +The simplest way to arrange to use this driver is to just list it in the +spi_board_info for a device as the driver it should use: the "modalias" +entry is "spidev", matching the name of the driver exposing this API. +Set up the other device characteristics (bits per word, SPI clocking, +chipselect polarity, etc) as usual, so you won't always need to override +them later. + +(Sysfs also supports userspace driven binding/unbinding of drivers to +devices. That mechanism might be supported here in the future.) + +When you do that, the sysfs node for the SPI device will include a child +device node with a "dev" attribute that will be understood by udev or mdev. +(Larger systems will have "udev". Smaller ones may configure "mdev" into +busybox; it's less featureful, but often enough.) For a SPI device with +chipselect C on bus B, you should see: + + /dev/spidevB.C ... character special device, major number 153 with + a dynamically chosen minor device number. This is the node + that userspace programs will open, created by "udev" or "mdev". + + /sys/devices/.../spiB.C ... as usual, the SPI device node will + be a child of its SPI master controller. + + /sys/class/spidev/spidevB.C ... created when the "spidev" driver + binds to that device. (Directory or symlink, based on whether + or not you enabled the "deprecated sysfs files" Kconfig option.) + +Do not try to manage the /dev character device special file nodes by hand. +That's error prone, and you'd need to pay careful attention to system +security issues; udev/mdev should already be configured securely. + +If you unbind the "spidev" driver from that device, those two "spidev" nodes +(in sysfs and in /dev) should automatically be removed (respectively by the +kernel and by udev/mdev). You can unbind by removing the "spidev" driver +module, which will affect all devices using this driver. You can also unbind +by having kernel code remove the SPI device, probably by removing the driver +for its SPI controller (so its spi_master vanishes). + +Since this is a standard Linux device driver -- even though it just happens +to expose a low level API to userspace -- it can be associated with any number +of devices at a time. Just provide one spi_board_info record for each such +SPI device, and you'll get a /dev device node for each device. + + +BASIC CHARACTER DEVICE API +========================== +Normal open() and close() operations on /dev/spidevB.D files work as you +would expect. + +Standard read() and write() operations are obviously only half-duplex, and +the chipselect is deactivated between those operations. Full-duplex access, +and composite operation without chipselect de-activation, is available using +the SPI_IOC_MESSAGE(N) request. + +Several ioctl() requests let your driver read or override the device's current +settings for data transfer parameters: + + SPI_IOC_RD_MODE, SPI_IOC_WR_MODE ... pass a pointer to a byte which will + return (RD) or assign (WR) the SPI transfer mode. Use the constants + SPI_MODE_0..SPI_MODE_3; or if you prefer you can combine SPI_CPOL + (clock polarity, idle high iff this is set) or SPI_CPHA (clock phase, + sample on trailing edge iff this is set) flags. + + SPI_IOC_RD_LSB_FIRST, SPI_IOC_WR_LSB_FIRST ... pass a pointer to a byte + which will return (RD) or assign (WR) the bit justification used to + transfer SPI words. Zero indicates MSB-first; other values indicate + the less common LSB-first encoding. In both cases the specified value + is right-justified in each word, so that unused (TX) or undefined (RX) + bits are in the MSBs. + + SPI_IOC_RD_BITS_PER_WORD, SPI_IOC_WR_BITS_PER_WORD ... pass a pointer to + a byte which will return (RD) or assign (WR) the number of bits in + each SPI transfer word. The value zero signifies eight bits. + + SPI_IOC_RD_MAX_SPEED_HZ, SPI_IOC_WR_MAX_SPEED_HZ ... pass a pointer to a + u32 which will return (RD) or assign (WR) the maximum SPI transfer + speed, in Hz. The controller can't necessarily assign that specific + clock speed. + +NOTES: + + - At this time there is no async I/O support; everything is purely + synchronous. + + - There's currently no way to report the actual bit rate used to + shift data to/from a given device. + + - From userspace, you can't currently change the chip select polarity; + that could corrupt transfers to other devices sharing the SPI bus. + Each SPI device is deselected when it's not in active use, allowing + other drivers to talk to other devices. + + - There's a limit on the number of bytes each I/O request can transfer + to the SPI device. It defaults to one page, but that can be changed + using a module parameter. + + - Because SPI has no low-level transfer acknowledgement, you usually + won't see any I/O errors when talking to a non-existent device. + + +FULL DUPLEX CHARACTER DEVICE API +================================ + +See the sample program below for one example showing the use of the full +duplex programming interface. (Although it doesn't perform a full duplex +transfer.) The model is the same as that used in the kernel spi_sync() +request; the individual transfers offer the same capabilities as are +available to kernel drivers (except that it's not asynchronous). + +The example shows one half-duplex RPC-style request and response message. +These requests commonly require that the chip not be deselected between +the request and response. Several such requests could be chained into +a single kernel request, even allowing the chip to be deselected after +each response. (Other protocol options include changing the word size +and bitrate for each transfer segment.) + +To make a full duplex request, provide both rx_buf and tx_buf for the +same transfer. It's even OK if those are the same buffer. + + +SAMPLE PROGRAM +============== + +-------------------------------- CUT HERE +#include <stdio.h> +#include <unistd.h> +#include <stdlib.h> +#include <fcntl.h> +#include <string.h> + +#include <sys/ioctl.h> +#include <sys/types.h> +#include <sys/stat.h> + +#include <linux/types.h> +#include <linux/spi/spidev.h> + + +static int verbose; + +static void do_read(int fd, int len) +{ + unsigned char buf[32], *bp; + int status; + + /* read at least 2 bytes, no more than 32 */ + if (len < 2) + len = 2; + else if (len > sizeof(buf)) + len = sizeof(buf); + memset(buf, 0, sizeof buf); + + status = read(fd, buf, len); + if (status < 0) { + perror("read"); + return; + } + if (status != len) { + fprintf(stderr, "short read\n"); + return; + } + + printf("read(%2d, %2d): %02x %02x,", len, status, + buf[0], buf[1]); + status -= 2; + bp = buf + 2; + while (status-- > 0) + printf(" %02x", *bp++); + printf("\n"); +} + +static void do_msg(int fd, int len) +{ + struct spi_ioc_transfer xfer[2]; + unsigned char buf[32], *bp; + int status; + + memset(xfer, 0, sizeof xfer); + memset(buf, 0, sizeof buf); + + if (len > sizeof buf) + len = sizeof buf; + + buf[0] = 0xaa; + xfer[0].tx_buf = (__u64) buf; + xfer[0].len = 1; + + xfer[1].rx_buf = (__u64) buf; + xfer[1].len = len; + + status = ioctl(fd, SPI_IOC_MESSAGE(2), xfer); + if (status < 0) { + perror("SPI_IOC_MESSAGE"); + return; + } + + printf("response(%2d, %2d): ", len, status); + for (bp = buf; len; len--) + printf(" %02x", *bp++); + printf("\n"); +} + +static void dumpstat(const char *name, int fd) +{ + __u8 mode, lsb, bits; + __u32 speed; + + if (ioctl(fd, SPI_IOC_RD_MODE, &mode) < 0) { + perror("SPI rd_mode"); + return; + } + if (ioctl(fd, SPI_IOC_RD_LSB_FIRST, &lsb) < 0) { + perror("SPI rd_lsb_fist"); + return; + } + if (ioctl(fd, SPI_IOC_RD_BITS_PER_WORD, &bits) < 0) { + perror("SPI bits_per_word"); + return; + } + if (ioctl(fd, SPI_IOC_RD_MAX_SPEED_HZ, &speed) < 0) { + perror("SPI max_speed_hz"); + return; + } + + printf("%s: spi mode %d, %d bits %sper word, %d Hz max\n", + name, mode, bits, lsb ? "(lsb first) " : "", speed); +} + +int main(int argc, char **argv) +{ + int c; + int readcount = 0; + int msglen = 0; + int fd; + const char *name; + + while ((c = getopt(argc, argv, "hm:r:v")) != EOF) { + switch (c) { + case 'm': + msglen = atoi(optarg); + if (msglen < 0) + goto usage; + continue; + case 'r': + readcount = atoi(optarg); + if (readcount < 0) + goto usage; + continue; + case 'v': + verbose++; + continue; + case 'h': + case '?': +usage: + fprintf(stderr, + "usage: %s [-h] [-m N] [-r N] /dev/spidevB.D\n", + argv[0]); + return 1; + } + } + + if ((optind + 1) != argc) + goto usage; + name = argv[optind]; + + fd = open(name, O_RDWR); + if (fd < 0) { + perror("open"); + return 1; + } + + dumpstat(name, fd); + + if (msglen) + do_msg(fd, msglen); + + if (readcount) + do_read(fd, readcount); + + close(fd); + return 0; +} diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig index 4a012d9acbff..584ed9f74700 100644 --- a/drivers/spi/Kconfig +++ b/drivers/spi/Kconfig @@ -159,6 +159,15 @@ config SPI_AT25 This driver can also be built as a module. If so, the module will be called at25. +config SPI_SPIDEV + tristate "User mode SPI device driver support" + depends on SPI_MASTER && EXPERIMENTAL + help + This supports user mode SPI protocol drivers. + + Note that this application programming interface is EXPERIMENTAL + and hence SUBJECT TO CHANGE WITHOUT NOTICE while it stabilizes. + # # Add new SPI protocol masters in alphabetical order above this line # diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile index a95ade857a2f..4cc5e99dd59a 100644 --- a/drivers/spi/Makefile +++ b/drivers/spi/Makefile @@ -25,6 +25,7 @@ obj-$(CONFIG_SPI_S3C24XX) += spi_s3c24xx.o # SPI protocol drivers (device/link on bus) obj-$(CONFIG_SPI_AT25) += at25.o +obj-$(CONFIG_SPI_SPIDEV) += spidev.o # ... add above this line ... # SPI slave controller drivers (upstream link) diff --git a/drivers/spi/spidev.c b/drivers/spi/spidev.c new file mode 100644 index 000000000000..c0a6dce800a3 --- /dev/null +++ b/drivers/spi/spidev.c @@ -0,0 +1,584 @@ +/* + * spidev.c -- simple synchronous userspace interface to SPI devices + * + * Copyright (C) 2006 SWAPP + * Andrea Paterniani <a.paterniani@swapp-eng.it> + * Copyright (C) 2007 David Brownell (simplification, cleanup) + * + * 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. + * + * 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, write to the Free Software + * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + */ + +#include <linux/init.h> +#include <linux/module.h> +#include <linux/ioctl.h> +#include <linux/fs.h> +#include <linux/device.h> +#include <linux/list.h> +#include <linux/errno.h> +#include <linux/mutex.h> +#include <linux/slab.h> + +#include <linux/spi/spi.h> +#include <linux/spi/spidev.h> + +#include <asm/uaccess.h> + + +/* + * This supports acccess to SPI devices using normal userspace I/O calls. + * Note that while traditional UNIX/POSIX I/O semantics are half duplex, + * and often mask message boundaries, full SPI support requires full duplex + * transfers. There are several kinds of of internal message boundaries to + * handle chipselect management and other protocol options. + * + * SPI has a character major number assigned. We allocate minor numbers + * dynamically using a bitmask. You must use hotplug tools, such as udev + * (or mdev with busybox) to create and destroy the /dev/spidevB.C device + * nodes, since there is no fixed association of minor numbers with any + * particular SPI bus or device. + */ +#define SPIDEV_MAJOR 153 /* assigned */ +#define N_SPI_MINORS 32 /* ... up to 256 */ + +static unsigned long minors[N_SPI_MINORS / BITS_PER_LONG]; + + +/* Bit masks for spi_device.mode management */ +#define SPI_MODE_MASK (SPI_CPHA | SPI_CPOL) + + +struct spidev_data { + struct device dev; + struct spi_device *spi; + struct list_head device_entry; + + struct mutex buf_lock; + unsigned users; + u8 *buffer; +}; + +static LIST_HEAD(device_list); +static DEFINE_MUTEX(device_list_lock); + +static unsigned bufsiz = 4096; +module_param(bufsiz, uint, S_IRUGO); +MODULE_PARM_DESC(bufsiz, "data bytes in biggest supported SPI message"); + +/*-------------------------------------------------------------------------*/ + +/* Read-only message with current device setup */ +static ssize_t +spidev_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos) +{ + struct spidev_data *spidev; + struct spi_device *spi; + ssize_t status = 0; + + /* chipselect only toggles at start or end of operation */ + if (count > bufsiz) + return -EMSGSIZE; + + spidev = filp->private_data; + spi = spidev->spi; + + mutex_lock(&spidev->buf_lock); + status = spi_read(spi, spidev->buffer, count); + if (status == 0) { + unsigned long missing; + + missing = copy_to_user(buf, spidev->buffer, count); + if (count && missing == count) + status = -EFAULT; + else + status = count - missing; + } + mutex_unlock(&spidev->buf_lock); + + return status; +} + +/* Write-only message with current device setup */ +static ssize_t +spidev_write(struct file *filp, const char __user *buf, + size_t count, loff_t *f_pos) +{ + struct spidev_data *spidev; + struct spi_device *spi; + ssize_t status = 0; + unsigned long missing; + + /* chipselect only toggles at start or end of operation */ + if (count > bufsiz) + return -EMSGSIZE; + + spidev = filp->private_data; + spi = spidev->spi; + + mutex_lock(&spidev->buf_lock); + missing = copy_from_user(spidev->buffer, buf, count); + if (missing == 0) { + status = spi_write(spi, spidev->buffer, count); + if (status == 0) + status = count; + } else + status = -EFAULT; + mutex_unlock(&spidev->buf_lock); + + return status; +} + +static int spidev_message(struct spidev_data *spidev, + struct spi_ioc_transfer *u_xfers, unsigned n_xfers) +{ + struct spi_message msg; + struct spi_transfer *k_xfers; + struct spi_transfer *k_tmp; + struct spi_ioc_transfer *u_tmp; + struct spi_device *spi = spidev->spi; + unsigned n, total; + u8 *buf; + int status = -EFAULT; + + spi_message_init(&msg); + k_xfers = kcalloc(n_xfers, sizeof(*k_tmp), GFP_KERNEL); + if (k_xfers == NULL) + return -ENOMEM; + + /* Construct spi_message, copying any tx data to bounce buffer. + * We walk the array of user-provided transfers, using each one + * to initialize a kernel version of the same transfer. + */ + mutex_lock(&spidev->buf_lock); + buf = spidev->buffer; + total = 0; + for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers; + n; + n--, k_tmp++, u_tmp++) { + k_tmp->len = u_tmp->len; + + if (u_tmp->rx_buf) { + k_tmp->rx_buf = buf; + if (!access_ok(VERIFY_WRITE, u_tmp->rx_buf, u_tmp->len)) + goto done; + } + if (u_tmp->tx_buf) { + k_tmp->tx_buf = buf; + if (copy_from_user(buf, (const u8 __user *)u_tmp->tx_buf, + u_tmp->len)) + goto done; + } + + total += k_tmp->len; + if (total > bufsiz) { + status = -EMSGSIZE; + goto done; + } + buf += k_tmp->len; + + k_tmp->cs_change = !!u_tmp->cs_change; + k_tmp->bits_per_word = u_tmp->bits_per_word; + k_tmp->delay_usecs = u_tmp->delay_usecs; + k_tmp->speed_hz = u_tmp->speed_hz; +#ifdef VERBOSE + dev_dbg(&spi->dev, + " xfer len %zd %s%s%s%dbits %u usec %uHz\n", + u_tmp->len, + u_tmp->rx_buf ? "rx " : "", + u_tmp->tx_buf ? "tx " : "", + u_tmp->cs_change ? "cs " : "", + u_tmp->bits_per_word ? : spi->bits_per_word, + u_tmp->delay_usecs, + u_tmp->speed_hz ? : spi->max_speed_hz); +#endif + spi_message_add_tail(k_tmp, &msg); + } + + status = spi_sync(spi, &msg); + if (status < 0) + goto done; + + /* copy any rx data out of bounce buffer */ + buf = spidev->buffer; + for (n = n_xfers, u_tmp = u_xfers; n; n--, u_tmp++) { + if (u_tmp->rx_buf) { + if (__copy_to_user((u8 __user *)u_tmp->rx_buf, buf, + u_tmp->len)) { + status = -EFAULT; + goto done; + } + } + buf += u_tmp->len; + } + status = total; + +done: + mutex_unlock(&spidev->buf_lock); + kfree(k_xfers); + return status; +} + +static int +spidev_ioctl(struct inode *inode, struct file *filp, + unsigned int cmd, unsigned long arg) +{ + int err = 0; + int retval = 0; + struct spidev_data *spidev; + struct spi_device *spi; + u32 tmp; + unsigned n_ioc; + struct spi_ioc_transfer *ioc; + + /* Check type and command number */ + if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC) + return -ENOTTY; + + /* Check access direction once here; don't repeat below. + * IOC_DIR is from the user perspective, while access_ok is + * from the kernel perspective; so they look reversed. + */ + if (_IOC_DIR(cmd) & _IOC_READ) + err = !access_ok(VERIFY_WRITE, + (void __user *)arg, _IOC_SIZE(cmd)); + if (err == 0 && _IOC_DIR(cmd) & _IOC_WRITE) + err = !access_ok(VERIFY_READ, + (void __user *)arg, _IOC_SIZE(cmd)); + if (err) + return -EFAULT; + + spidev = filp->private_data; + spi = spidev->spi; + + switch (cmd) { + /* read requests */ + case SPI_IOC_RD_MODE: + retval = __put_user(spi->mode & SPI_MODE_MASK, + (__u8 __user *)arg); + break; + case SPI_IOC_RD_LSB_FIRST: + retval = __put_user((spi->mode & SPI_LSB_FIRST) ? 1 : 0, + (__u8 __user *)arg); + break; + case SPI_IOC_RD_BITS_PER_WORD: + retval = __put_user(spi->bits_per_word, (__u8 __user *)arg); + break; + case SPI_IOC_RD_MAX_SPEED_HZ: + retval = __put_user(spi->max_speed_hz, (__u32 __user *)arg); + break; + + /* write requests */ + case SPI_IOC_WR_MODE: + retval = __get_user(tmp, (u8 __user *)arg); + if (retval == 0) { + u8 save = spi->mode; + + if (tmp & ~SPI_MODE_MASK) { + retval = -EINVAL; + break; + } + + tmp |= spi->mode & ~SPI_MODE_MASK; + spi->mode = (u8)tmp; + retval = spi_setup(spi); + if (retval < 0) + spi->mode = save; + else + dev_dbg(&spi->dev, "spi mode %02x\n", tmp); + } + break; + case SPI_IOC_WR_LSB_FIRST: + retval = __get_user(tmp, (__u8 __user *)arg); + if (retval == 0) { + u8 save = spi->mode; + + if (tmp) + spi->mode |= SPI_LSB_FIRST; + else + spi->mode &= ~SPI_LSB_FIRST; + retval = spi_setup(spi); + if (retval < 0) + spi->mode = save; + else + dev_dbg(&spi->dev, "%csb first\n", + tmp ? 'l' : 'm'); + } + break; + case SPI_IOC_WR_BITS_PER_WORD: + retval = __get_user(tmp, (__u8 __user *)arg); + if (retval == 0) { + u8 save = spi->bits_per_word; + + spi->bits_per_word = tmp; + retval = spi_setup(spi); + if (retval < 0) + spi->bits_per_word = save; + else + dev_dbg(&spi->dev, "%d bits per word\n", tmp); + } + break; + case SPI_IOC_WR_MAX_SPEED_HZ: + retval = __get_user(tmp, (__u32 __user *)arg); + if (retval == 0) { + u32 save = spi->max_speed_hz; + + spi->max_speed_hz = tmp; + retval = spi_setup(spi); + if (retval < 0) + spi->max_speed_hz = save; + else + dev_dbg(&spi->dev, "%d Hz (max)\n", tmp); + } + break; + + default: + /* segmented and/or full-duplex I/O request */ + if (_IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0)) + || _IOC_DIR(cmd) != _IOC_WRITE) + return -ENOTTY; + + tmp = _IOC_SIZE(cmd); + if ((tmp % sizeof(struct spi_ioc_transfer)) != 0) { + retval = -EINVAL; + break; + } + n_ioc = tmp / sizeof(struct spi_ioc_transfer); + if (n_ioc == 0) + break; + + /* copy into scratch area */ + ioc = kmalloc(tmp, GFP_KERNEL); + if (!ioc) { + retval = -ENOMEM; + break; + } + if (__copy_from_user(ioc, (void __user *)arg, tmp)) { + retval = -EFAULT; + break; + } + + /* translate to spi_message, execute */ + retval = spidev_message(spidev, ioc, n_ioc); + kfree(ioc); + break; + } + return retval; +} + +static int spidev_open(struct inode *inode, struct file *filp) +{ + struct spidev_data *spidev; + int status = -ENXIO; + + mutex_lock(&device_list_lock); + + list_for_each_entry(spidev, &device_list, device_entry) { + if (spidev->dev.devt == inode->i_rdev) { + status = 0; + break; + } + } + if (status == 0) { + if (!spidev->buffer) { + spidev->buffer = kmalloc(bufsiz, GFP_KERNEL); + if (!spidev->buffer) { + dev_dbg(&spidev->spi->dev, "open/ENOMEM\n"); + status = -ENOMEM; + } + } + if (status == 0) { + spidev->users++; + filp->private_data = spidev; + nonseekable_open(inode, filp); + } + } else + pr_debug("spidev: nothing for minor %d\n", iminor(inode)); + + mutex_unlock(&device_list_lock); + return status; +} + +static int spidev_release(struct inode *inode, struct file *filp) +{ + struct spidev_data *spidev; + int status = 0; + + mutex_lock(&device_list_lock); + spidev = filp->private_data; + filp->private_data = NULL; + spidev->users--; + if (!spidev->users) { + kfree(spidev->buffer); + spidev->buffer = NULL; + } + mutex_unlock(&device_list_lock); + + return status; +} + +static struct file_operations spidev_fops = { + .owner = THIS_MODULE, + /* REVISIT switch to aio primitives, so that userspace + * gets more complete API coverage. It'll simplify things + * too, except for the locking. + */ + .write = spidev_write, + .read = spidev_read, + .ioctl = spidev_ioctl, + .open = spidev_open, + .release = spidev_release, +}; + +/*-------------------------------------------------------------------------*/ + +/* The main reason to have this class is to make mdev/udev create the + * /dev/spidevB.C character device nodes exposing our userspace API. + * It also simplifies memory management. + */ + +static void spidev_classdev_release(struct device *dev) +{ + struct spidev_data *spidev; + + spidev = container_of(dev, struct spidev_data, dev); + kfree(spidev); +} + +static struct class spidev_class = { + .name = "spidev", + .owner = THIS_MODULE, + .dev_release = spidev_classdev_release, +}; + +/*-------------------------------------------------------------------------*/ + +static int spidev_probe(struct spi_device *spi) +{ + struct spidev_data *spidev; + int status; + unsigned long minor; + + /* Allocate driver data */ + spidev = kzalloc(sizeof(*spidev), GFP_KERNEL); + if (!spidev) + return -ENOMEM; + + /* Initialize the driver data */ + spidev->spi = spi; + mutex_init(&spidev->buf_lock); + + INIT_LIST_HEAD(&spidev->device_entry); + + /* If we can allocate a minor number, hook up this device. + * Reusing minors is fine so long as udev or mdev is working. + */ + mutex_lock(&device_list_lock); + minor = find_first_zero_bit(minors, ARRAY_SIZE(minors)); + if (minor < N_SPI_MINORS) { + spidev->dev.parent = &spi->dev; + spidev->dev.class = &spidev_class; + spidev->dev.devt = MKDEV(SPIDEV_MAJOR, minor); + snprintf(spidev->dev.bus_id, sizeof spidev->dev.bus_id, + "spidev%d.%d", + spi->master->bus_num, spi->chip_select); + status = device_register(&spidev->dev); + } else { + dev_dbg(&spi->dev, "no minor number available!\n"); + status = -ENODEV; + } + if (status == 0) { + set_bit(minor, minors); + dev_set_drvdata(&spi->dev, spidev); + list_add(&spidev->device_entry, &device_list); + } + mutex_unlock(&device_list_lock); + + if (status != 0) + kfree(spidev); + + return status; +} + +static int spidev_remove(struct spi_device *spi) +{ + struct spidev_data *spidev = dev_get_drvdata(&spi->dev); + + mutex_lock(&device_list_lock); + + list_del(&spidev->device_entry); + dev_set_drvdata(&spi->dev, NULL); + clear_bit(MINOR(spidev->dev.devt), minors); + device_unregister(&spidev->dev); + + mutex_unlock(&device_list_lock); + + return 0; +} + +static struct spi_driver spidev_spi = { + .driver = { + .name = "spidev", + .owner = THIS_MODULE, + }, + .probe = spidev_probe, + .remove = __devexit_p(spidev_remove), + + /* NOTE: suspend/resume methods are not necessary here. + * We don't do anything except pass the requests to/from + * the underlying controller. The refrigerator handles + * most issues; the controller driver handles the rest. + */ +}; + +/*-------------------------------------------------------------------------*/ + +static int __init spidev_init(void) +{ + int status; + + /* Claim our 256 reserved device numbers. Then register a class + * that will key udev/mdev to add/remove /dev nodes. Last, register + * the driver which manages those device numbers. + */ + BUILD_BUG_ON(N_SPI_MINORS > 256); + status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops); + if (status < 0) + return status; + + status = class_register(&spidev_class); + if (status < 0) { + unregister_chrdev(SPIDEV_MAJOR, spidev_spi.driver.name); + return status; + } + + status = spi_register_driver(&spidev_spi); + if (status < 0) { + class_unregister(&spidev_class); + unregister_chrdev(SPIDEV_MAJOR, spidev_spi.driver.name); + } + return status; +} +module_init(spidev_init); + +static void __exit spidev_exit(void) +{ + spi_unregister_driver(&spidev_spi); + class_unregister(&spidev_class); + unregister_chrdev(SPIDEV_MAJOR, spidev_spi.driver.name); +} +module_exit(spidev_exit); + +MODULE_AUTHOR("Andrea Paterniani, <a.paterniani@swapp-eng.it>"); +MODULE_DESCRIPTION("User mode SPI device interface"); +MODULE_LICENSE("GPL"); diff --git a/include/linux/Kbuild b/include/linux/Kbuild index 715386142626..ccc6fc157064 100644 --- a/include/linux/Kbuild +++ b/include/linux/Kbuild @@ -4,6 +4,7 @@ header-y += hdlc/ header-y += isdn/ header-y += nfsd/ header-y += raid/ +header-y += spi/ header-y += sunrpc/ header-y += tc_act/ header-y += netfilter/ diff --git a/include/linux/spi/Kbuild b/include/linux/spi/Kbuild new file mode 100644 index 000000000000..d375a082986e --- /dev/null +++ b/include/linux/spi/Kbuild @@ -0,0 +1 @@ +header-y += spidev.h diff --git a/include/linux/spi/spidev.h b/include/linux/spi/spidev.h new file mode 100644 index 000000000000..7d700be57490 --- /dev/null +++ b/include/linux/spi/spidev.h @@ -0,0 +1,124 @@ +/* + * include/linux/spi/spidev.h + * + * Copyright (C) 2006 SWAPP + * Andrea Paterniani <a.paterniani@swapp-eng.it> + * + * 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. + * + * 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, write to the Free Software + * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + */ + +#ifndef SPIDEV_H +#define SPIDEV_H + + +/* User space versions of kernel symbols for SPI clocking modes, + * matching <linux/spi/spi.h> + */ + +#define SPI_CPHA 0x01 +#define SPI_CPOL 0x02 + +#define SPI_MODE_0 (0|0) +#define SPI_MODE_1 (0|SPI_CPHA) +#define SPI_MODE_2 (SPI_CPOL|0) +#define SPI_MODE_3 (SPI_CPOL|SPI_CPHA) + + +/*---------------------------------------------------------------------------*/ + +/* IOCTL commands */ + +#define SPI_IOC_MAGIC 'k' + +/** + * struct spi_ioc_transfer - describes a single SPI transfer + * @tx_buf: Holds pointer to userspace buffer with transmit data, or null. + * If no data is provided, zeroes are shifted out. + * @rx_buf: Holds pointer to userspace buffer for receive data, or null. + * @len: Length of tx and rx buffers, in bytes. + * @speed_hz: Temporary override of the device's bitrate. + * @bits_per_word: Temporary override of the device's wordsize. + * @delay_usecs: If nonzero, how long to delay after the last bit transfer + * before optionally deselecting the device before the next transfer. + * @cs_change: True to deselect device before starting the next transfer. + * + * This structure is mapped directly to the kernel spi_transfer structure; + * the fields have the same meanings, except of course that the pointers + * are in a different address space (and may be of different sizes in some + * cases, such as 32-bit i386 userspace over a 64-bit x86_64 kernel). + * Zero-initialize the structure, including currently unused fields, to + * accomodate potential future updates. + * + * SPI_IOC_MESSAGE gives userspace the equivalent of kernel spi_sync(). + * Pass it an array of related transfers, they'll execute together. + * Each transfer may be half duplex (either direction) or full duplex. + * + * struct spi_ioc_transfer mesg[4]; + * ... + * status = ioctl(fd, SPI_IOC_MESSAGE(4), mesg); + * + * So for example one transfer might send a nine bit command (right aligned + * in a 16-bit word), the next could read a block of 8-bit data before + * terminating that command by temporarily deselecting the chip; the next + * could send a different nine bit command (re-selecting the chip), and the + * last transfer might write some register values. + */ +struct spi_ioc_transfer { + __u64 tx_buf; + __u64 rx_buf; + + __u32 len; + __u32 speed_hz; + + __u16 delay_usecs; + __u8 bits_per_word; + __u8 cs_change; + __u32 pad; + + /* If the contents of 'struct spi_ioc_transfer' ever change + * incompatibly, then the ioctl number (currently 0) must change; + * ioctls with constant size fields get a bit more in the way of + * error checking than ones (like this) where that field varies. + * + * NOTE: struct layout is the same in 64bit and 32bit userspace. + */ +}; + +/* not all platforms use <asm-generic/ioctl.h> or _IOC_TYPECHECK() ... */ +#define SPI_MSGSIZE(N) \ + ((((N)*(sizeof (struct spi_ioc_transfer))) < (1 << _IOC_SIZEBITS)) \ + ? ((N)*(sizeof (struct spi_ioc_transfer))) : 0) +#define SPI_IOC_MESSAGE(N) _IOW(SPI_IOC_MAGIC, 0, char[SPI_MSGSIZE(N)]) + + +/* Read / Write of SPI mode (SPI_MODE_0..SPI_MODE_3) */ +#define SPI_IOC_RD_MODE _IOR(SPI_IOC_MAGIC, 1, __u8) +#define SPI_IOC_WR_MODE _IOW(SPI_IOC_MAGIC, 1, __u8) + +/* Read / Write SPI bit justification */ +#define SPI_IOC_RD_LSB_FIRST _IOR(SPI_IOC_MAGIC, 2, __u8) +#define SPI_IOC_WR_LSB_FIRST _IOW(SPI_IOC_MAGIC, 2, __u8) + +/* Read / Write SPI device word length (1..N) */ +#define SPI_IOC_RD_BITS_PER_WORD _IOR(SPI_IOC_MAGIC, 3, __u8) +#define SPI_IOC_WR_BITS_PER_WORD _IOW(SPI_IOC_MAGIC, 3, __u8) + +/* Read / Write SPI device default max speed hz */ +#define SPI_IOC_RD_MAX_SPEED_HZ _IOR(SPI_IOC_MAGIC, 4, __u32) +#define SPI_IOC_WR_MAX_SPEED_HZ _IOW(SPI_IOC_MAGIC, 4, __u32) + + + +#endif /* SPIDEV_H */ |