![Arnd Bergmann](/assets/img/avatar_default.png)
All file_operations should get a .llseek operation so we can make nonseekable_open the default for future file operations without a .llseek pointer. The three cases that we can automatically detect are no_llseek, seq_lseek and default_llseek. For cases where we can we can automatically prove that the file offset is always ignored, we use noop_llseek, which maintains the current behavior of not returning an error from a seek. New drivers should normally not use noop_llseek but instead use no_llseek and call nonseekable_open at open time. Existing drivers can be converted to do the same when the maintainer knows for certain that no user code relies on calling seek on the device file. The generated code is often incorrectly indented and right now contains comments that clarify for each added line why a specific variant was chosen. In the version that gets submitted upstream, the comments will be gone and I will manually fix the indentation, because there does not seem to be a way to do that using coccinelle. Some amount of new code is currently sitting in linux-next that should get the same modifications, which I will do at the end of the merge window. Many thanks to Julia Lawall for helping me learn to write a semantic patch that does all this. ===== begin semantic patch ===== // This adds an llseek= method to all file operations, // as a preparation for making no_llseek the default. // // The rules are // - use no_llseek explicitly if we do nonseekable_open // - use seq_lseek for sequential files // - use default_llseek if we know we access f_pos // - use noop_llseek if we know we don't access f_pos, // but we still want to allow users to call lseek // @ open1 exists @ identifier nested_open; @@ nested_open(...) { <+... nonseekable_open(...) ...+> } @ open exists@ identifier open_f; identifier i, f; identifier open1.nested_open; @@ int open_f(struct inode *i, struct file *f) { <+... ( nonseekable_open(...) | nested_open(...) ) ...+> } @ read disable optional_qualifier exists @ identifier read_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; expression E; identifier func; @@ ssize_t read_f(struct file *f, char *p, size_t s, loff_t *off) { <+... ( *off = E | *off += E | func(..., off, ...) | E = *off ) ...+> } @ read_no_fpos disable optional_qualifier exists @ identifier read_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; @@ ssize_t read_f(struct file *f, char *p, size_t s, loff_t *off) { ... when != off } @ write @ identifier write_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; expression E; identifier func; @@ ssize_t write_f(struct file *f, const char *p, size_t s, loff_t *off) { <+... ( *off = E | *off += E | func(..., off, ...) | E = *off ) ...+> } @ write_no_fpos @ identifier write_f; identifier f, p, s, off; type ssize_t, size_t, loff_t; @@ ssize_t write_f(struct file *f, const char *p, size_t s, loff_t *off) { ... when != off } @ fops0 @ identifier fops; @@ struct file_operations fops = { ... }; @ has_llseek depends on fops0 @ identifier fops0.fops; identifier llseek_f; @@ struct file_operations fops = { ... .llseek = llseek_f, ... }; @ has_read depends on fops0 @ identifier fops0.fops; identifier read_f; @@ struct file_operations fops = { ... .read = read_f, ... }; @ has_write depends on fops0 @ identifier fops0.fops; identifier write_f; @@ struct file_operations fops = { ... .write = write_f, ... }; @ has_open depends on fops0 @ identifier fops0.fops; identifier open_f; @@ struct file_operations fops = { ... .open = open_f, ... }; // use no_llseek if we call nonseekable_open //////////////////////////////////////////// @ nonseekable1 depends on !has_llseek && has_open @ identifier fops0.fops; identifier nso ~= "nonseekable_open"; @@ struct file_operations fops = { ... .open = nso, ... +.llseek = no_llseek, /* nonseekable */ }; @ nonseekable2 depends on !has_llseek @ identifier fops0.fops; identifier open.open_f; @@ struct file_operations fops = { ... .open = open_f, ... +.llseek = no_llseek, /* open uses nonseekable */ }; // use seq_lseek for sequential files ///////////////////////////////////// @ seq depends on !has_llseek @ identifier fops0.fops; identifier sr ~= "seq_read"; @@ struct file_operations fops = { ... .read = sr, ... +.llseek = seq_lseek, /* we have seq_read */ }; // use default_llseek if there is a readdir /////////////////////////////////////////// @ fops1 depends on !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier readdir_e; @@ // any other fop is used that changes pos struct file_operations fops = { ... .readdir = readdir_e, ... +.llseek = default_llseek, /* readdir is present */ }; // use default_llseek if at least one of read/write touches f_pos ///////////////////////////////////////////////////////////////// @ fops2 depends on !fops1 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier read.read_f; @@ // read fops use offset struct file_operations fops = { ... .read = read_f, ... +.llseek = default_llseek, /* read accesses f_pos */ }; @ fops3 depends on !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier write.write_f; @@ // write fops use offset struct file_operations fops = { ... .write = write_f, ... + .llseek = default_llseek, /* write accesses f_pos */ }; // Use noop_llseek if neither read nor write accesses f_pos /////////////////////////////////////////////////////////// @ fops4 depends on !fops1 && !fops2 && !fops3 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier read_no_fpos.read_f; identifier write_no_fpos.write_f; @@ // write fops use offset struct file_operations fops = { ... .write = write_f, .read = read_f, ... +.llseek = noop_llseek, /* read and write both use no f_pos */ }; @ depends on has_write && !has_read && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier write_no_fpos.write_f; @@ struct file_operations fops = { ... .write = write_f, ... +.llseek = noop_llseek, /* write uses no f_pos */ }; @ depends on has_read && !has_write && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; identifier read_no_fpos.read_f; @@ struct file_operations fops = { ... .read = read_f, ... +.llseek = noop_llseek, /* read uses no f_pos */ }; @ depends on !has_read && !has_write && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @ identifier fops0.fops; @@ struct file_operations fops = { ... +.llseek = noop_llseek, /* no read or write fn */ }; ===== End semantic patch ===== Signed-off-by: Arnd Bergmann <arnd@arndb.de> Cc: Julia Lawall <julia@diku.dk> Cc: Christoph Hellwig <hch@infradead.org>
260 lines
5.8 KiB
C
260 lines
5.8 KiB
C
/*
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* AMD CS5535/CS5536 GPIO driver.
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* Allows a user space process to play with the GPIO pins.
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*
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* Copyright (c) 2005 Ben Gardner <bgardner@wabtec.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the smems of the GNU General Public License as published by
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* the Free Software Foundation; version 2 of the License.
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*/
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#include <linux/fs.h>
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#include <linux/module.h>
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#include <linux/errno.h>
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/cdev.h>
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#include <linux/ioport.h>
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#include <linux/pci.h>
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#include <asm/uaccess.h>
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#include <asm/io.h>
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#define NAME "cs5535_gpio"
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MODULE_AUTHOR("Ben Gardner <bgardner@wabtec.com>");
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MODULE_DESCRIPTION("AMD CS5535/CS5536 GPIO Pin Driver");
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MODULE_LICENSE("GPL");
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static int major;
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module_param(major, int, 0);
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MODULE_PARM_DESC(major, "Major device number");
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static ulong mask;
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module_param(mask, ulong, 0);
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MODULE_PARM_DESC(mask, "GPIO channel mask");
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#define MSR_LBAR_GPIO 0x5140000C
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static u32 gpio_base;
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static struct pci_device_id divil_pci[] = {
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{ PCI_DEVICE(PCI_VENDOR_ID_NS, PCI_DEVICE_ID_NS_CS5535_ISA) },
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{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_CS5536_ISA) },
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{ } /* NULL entry */
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};
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MODULE_DEVICE_TABLE(pci, divil_pci);
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static struct cdev cs5535_gpio_cdev;
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/* reserve 32 entries even though some aren't usable */
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#define CS5535_GPIO_COUNT 32
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/* IO block size */
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#define CS5535_GPIO_SIZE 256
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struct gpio_regmap {
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u32 rd_offset;
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u32 wr_offset;
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char on;
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char off;
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};
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static struct gpio_regmap rm[] =
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{
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{ 0x30, 0x00, '1', '0' }, /* GPIOx_READ_BACK / GPIOx_OUT_VAL */
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{ 0x20, 0x20, 'I', 'i' }, /* GPIOx_IN_EN */
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{ 0x04, 0x04, 'O', 'o' }, /* GPIOx_OUT_EN */
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{ 0x08, 0x08, 't', 'T' }, /* GPIOx_OUT_OD_EN */
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{ 0x18, 0x18, 'P', 'p' }, /* GPIOx_OUT_PU_EN */
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{ 0x1c, 0x1c, 'D', 'd' }, /* GPIOx_OUT_PD_EN */
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};
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/**
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* Gets the register offset for the GPIO bank.
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* Low (0-15) starts at 0x00, high (16-31) starts at 0x80
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*/
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static inline u32 cs5535_lowhigh_base(int reg)
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{
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return (reg & 0x10) << 3;
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}
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static ssize_t cs5535_gpio_write(struct file *file, const char __user *data,
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size_t len, loff_t *ppos)
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{
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u32 m = iminor(file->f_path.dentry->d_inode);
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int i, j;
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u32 base = gpio_base + cs5535_lowhigh_base(m);
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u32 m0, m1;
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char c;
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/**
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* Creates the mask for atomic bit programming.
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* The high 16 bits and the low 16 bits are used to set the mask.
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* For example, GPIO 15 maps to 31,15: 0,1 => On; 1,0=> Off
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*/
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m1 = 1 << (m & 0x0F);
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m0 = m1 << 16;
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for (i = 0; i < len; ++i) {
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if (get_user(c, data+i))
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return -EFAULT;
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for (j = 0; j < ARRAY_SIZE(rm); j++) {
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if (c == rm[j].on) {
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outl(m1, base + rm[j].wr_offset);
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/* If enabling output, turn off AUX 1 and AUX 2 */
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if (c == 'O') {
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outl(m0, base + 0x10);
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outl(m0, base + 0x14);
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}
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break;
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} else if (c == rm[j].off) {
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outl(m0, base + rm[j].wr_offset);
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break;
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}
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}
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}
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*ppos = 0;
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return len;
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}
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static ssize_t cs5535_gpio_read(struct file *file, char __user *buf,
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size_t len, loff_t *ppos)
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{
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u32 m = iminor(file->f_path.dentry->d_inode);
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u32 base = gpio_base + cs5535_lowhigh_base(m);
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int rd_bit = 1 << (m & 0x0f);
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int i;
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char ch;
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ssize_t count = 0;
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if (*ppos >= ARRAY_SIZE(rm))
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return 0;
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for (i = *ppos; (i < (*ppos + len)) && (i < ARRAY_SIZE(rm)); i++) {
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ch = (inl(base + rm[i].rd_offset) & rd_bit) ?
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rm[i].on : rm[i].off;
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if (put_user(ch, buf+count))
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return -EFAULT;
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count++;
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}
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/* add a line-feed if there is room */
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if ((i == ARRAY_SIZE(rm)) && (count < len)) {
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put_user('\n', buf + count);
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count++;
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}
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*ppos += count;
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return count;
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}
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static int cs5535_gpio_open(struct inode *inode, struct file *file)
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{
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u32 m = iminor(inode);
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/* the mask says which pins are usable by this driver */
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if ((mask & (1 << m)) == 0)
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return -EINVAL;
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return nonseekable_open(inode, file);
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}
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static const struct file_operations cs5535_gpio_fops = {
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.owner = THIS_MODULE,
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.write = cs5535_gpio_write,
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.read = cs5535_gpio_read,
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.open = cs5535_gpio_open,
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.llseek = no_llseek,
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};
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static int __init cs5535_gpio_init(void)
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{
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dev_t dev_id;
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u32 low, hi;
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int retval;
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if (pci_dev_present(divil_pci) == 0) {
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printk(KERN_WARNING NAME ": DIVIL not found\n");
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return -ENODEV;
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}
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/* Grab the GPIO I/O range */
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rdmsr(MSR_LBAR_GPIO, low, hi);
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/* Check the mask and whether GPIO is enabled (sanity check) */
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if (hi != 0x0000f001) {
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printk(KERN_WARNING NAME ": GPIO not enabled\n");
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return -ENODEV;
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}
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/* Mask off the IO base address */
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gpio_base = low & 0x0000ff00;
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/**
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* Some GPIO pins
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* 31-29,23 : reserved (always mask out)
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* 28 : Power Button
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* 26 : PME#
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* 22-16 : LPC
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* 14,15 : SMBus
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* 9,8 : UART1
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* 7 : PCI INTB
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* 3,4 : UART2/DDC
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* 2 : IDE_IRQ0
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* 0 : PCI INTA
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*
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* If a mask was not specified, be conservative and only allow:
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* 1,2,5,6,10-13,24,25,27
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*/
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if (mask != 0)
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mask &= 0x1f7fffff;
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else
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mask = 0x0b003c66;
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if (!request_region(gpio_base, CS5535_GPIO_SIZE, NAME)) {
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printk(KERN_ERR NAME ": can't allocate I/O for GPIO\n");
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return -ENODEV;
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}
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if (major) {
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dev_id = MKDEV(major, 0);
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retval = register_chrdev_region(dev_id, CS5535_GPIO_COUNT,
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NAME);
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} else {
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retval = alloc_chrdev_region(&dev_id, 0, CS5535_GPIO_COUNT,
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NAME);
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major = MAJOR(dev_id);
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}
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if (retval) {
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release_region(gpio_base, CS5535_GPIO_SIZE);
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return -1;
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}
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printk(KERN_DEBUG NAME ": base=%#x mask=%#lx major=%d\n",
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gpio_base, mask, major);
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cdev_init(&cs5535_gpio_cdev, &cs5535_gpio_fops);
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cdev_add(&cs5535_gpio_cdev, dev_id, CS5535_GPIO_COUNT);
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return 0;
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}
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static void __exit cs5535_gpio_cleanup(void)
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{
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dev_t dev_id = MKDEV(major, 0);
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cdev_del(&cs5535_gpio_cdev);
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unregister_chrdev_region(dev_id, CS5535_GPIO_COUNT);
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release_region(gpio_base, CS5535_GPIO_SIZE);
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}
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module_init(cs5535_gpio_init);
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module_exit(cs5535_gpio_cleanup);
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