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![Miguel Ojeda](/assets/img/avatar_default.png)
The warnings are: drivers/auxdisplay/img-ascii-lcd.c: warning: 'err' may be used uninitialized in this function [-Wuninitialized] At lines 109 and 207. Reported by Geert using the build service several times, e.g.: https://lkml.org/lkml/2018/2/19/303 They are two false positives, since num_chars > 0 in the three present configurations (boston, malta, sead3). Initialize to 0 in order to silence the warning. Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Paul Burton <paul.burton@mips.com> Signed-off-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
447 lines
11 KiB
C
447 lines
11 KiB
C
/*
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* Copyright (C) 2016 Imagination Technologies
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* Author: Paul Burton <paul.burton@mips.com>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version.
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*/
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#include <generated/utsrelease.h>
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#include <linux/kernel.h>
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#include <linux/io.h>
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#include <linux/mfd/syscon.h>
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#include <linux/module.h>
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#include <linux/of_address.h>
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#include <linux/of_platform.h>
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#include <linux/platform_device.h>
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#include <linux/regmap.h>
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#include <linux/slab.h>
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#include <linux/sysfs.h>
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struct img_ascii_lcd_ctx;
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/**
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* struct img_ascii_lcd_config - Configuration information about an LCD model
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* @num_chars: the number of characters the LCD can display
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* @external_regmap: true if registers are in a system controller, else false
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* @update: function called to update the LCD
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*/
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struct img_ascii_lcd_config {
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unsigned int num_chars;
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bool external_regmap;
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void (*update)(struct img_ascii_lcd_ctx *ctx);
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};
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/**
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* struct img_ascii_lcd_ctx - Private data structure
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* @pdev: the ASCII LCD platform device
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* @base: the base address of the LCD registers
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* @regmap: the regmap through which LCD registers are accessed
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* @offset: the offset within regmap to the start of the LCD registers
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* @cfg: pointer to the LCD model configuration
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* @message: the full message to display or scroll on the LCD
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* @message_len: the length of the @message string
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* @scroll_pos: index of the first character of @message currently displayed
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* @scroll_rate: scroll interval in jiffies
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* @timer: timer used to implement scrolling
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* @curr: the string currently displayed on the LCD
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*/
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struct img_ascii_lcd_ctx {
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struct platform_device *pdev;
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union {
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void __iomem *base;
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struct regmap *regmap;
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};
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u32 offset;
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const struct img_ascii_lcd_config *cfg;
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char *message;
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unsigned int message_len;
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unsigned int scroll_pos;
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unsigned int scroll_rate;
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struct timer_list timer;
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char curr[] __aligned(8);
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};
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/*
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* MIPS Boston development board
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*/
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static void boston_update(struct img_ascii_lcd_ctx *ctx)
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{
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ulong val;
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#if BITS_PER_LONG == 64
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val = *((u64 *)&ctx->curr[0]);
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__raw_writeq(val, ctx->base);
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#elif BITS_PER_LONG == 32
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val = *((u32 *)&ctx->curr[0]);
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__raw_writel(val, ctx->base);
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val = *((u32 *)&ctx->curr[4]);
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__raw_writel(val, ctx->base + 4);
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#else
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# error Not 32 or 64 bit
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#endif
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}
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static struct img_ascii_lcd_config boston_config = {
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.num_chars = 8,
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.update = boston_update,
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};
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/*
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* MIPS Malta development board
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*/
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static void malta_update(struct img_ascii_lcd_ctx *ctx)
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{
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unsigned int i;
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int err = 0;
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for (i = 0; i < ctx->cfg->num_chars; i++) {
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err = regmap_write(ctx->regmap,
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ctx->offset + (i * 8), ctx->curr[i]);
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if (err)
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break;
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}
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if (unlikely(err))
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pr_err_ratelimited("Failed to update LCD display: %d\n", err);
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}
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static struct img_ascii_lcd_config malta_config = {
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.num_chars = 8,
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.external_regmap = true,
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.update = malta_update,
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};
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/*
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* MIPS SEAD3 development board
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*/
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enum {
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SEAD3_REG_LCD_CTRL = 0x00,
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#define SEAD3_REG_LCD_CTRL_SETDRAM BIT(7)
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SEAD3_REG_LCD_DATA = 0x08,
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SEAD3_REG_CPLD_STATUS = 0x10,
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#define SEAD3_REG_CPLD_STATUS_BUSY BIT(0)
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SEAD3_REG_CPLD_DATA = 0x18,
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#define SEAD3_REG_CPLD_DATA_BUSY BIT(7)
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};
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static int sead3_wait_sm_idle(struct img_ascii_lcd_ctx *ctx)
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{
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unsigned int status;
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int err;
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do {
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err = regmap_read(ctx->regmap,
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ctx->offset + SEAD3_REG_CPLD_STATUS,
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&status);
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if (err)
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return err;
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} while (status & SEAD3_REG_CPLD_STATUS_BUSY);
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return 0;
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}
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static int sead3_wait_lcd_idle(struct img_ascii_lcd_ctx *ctx)
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{
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unsigned int cpld_data;
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int err;
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err = sead3_wait_sm_idle(ctx);
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if (err)
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return err;
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do {
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err = regmap_read(ctx->regmap,
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ctx->offset + SEAD3_REG_LCD_CTRL,
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&cpld_data);
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if (err)
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return err;
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err = sead3_wait_sm_idle(ctx);
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if (err)
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return err;
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err = regmap_read(ctx->regmap,
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ctx->offset + SEAD3_REG_CPLD_DATA,
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&cpld_data);
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if (err)
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return err;
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} while (cpld_data & SEAD3_REG_CPLD_DATA_BUSY);
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return 0;
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}
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static void sead3_update(struct img_ascii_lcd_ctx *ctx)
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{
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unsigned int i;
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int err = 0;
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for (i = 0; i < ctx->cfg->num_chars; i++) {
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err = sead3_wait_lcd_idle(ctx);
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if (err)
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break;
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err = regmap_write(ctx->regmap,
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ctx->offset + SEAD3_REG_LCD_CTRL,
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SEAD3_REG_LCD_CTRL_SETDRAM | i);
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if (err)
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break;
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err = sead3_wait_lcd_idle(ctx);
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if (err)
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break;
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err = regmap_write(ctx->regmap,
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ctx->offset + SEAD3_REG_LCD_DATA,
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ctx->curr[i]);
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if (err)
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break;
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}
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if (unlikely(err))
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pr_err_ratelimited("Failed to update LCD display: %d\n", err);
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}
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static struct img_ascii_lcd_config sead3_config = {
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.num_chars = 16,
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.external_regmap = true,
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.update = sead3_update,
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};
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static const struct of_device_id img_ascii_lcd_matches[] = {
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{ .compatible = "img,boston-lcd", .data = &boston_config },
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{ .compatible = "mti,malta-lcd", .data = &malta_config },
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{ .compatible = "mti,sead3-lcd", .data = &sead3_config },
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{ /* sentinel */ }
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};
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MODULE_DEVICE_TABLE(of, img_ascii_lcd_matches);
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/**
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* img_ascii_lcd_scroll() - scroll the display by a character
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* @t: really a pointer to the private data structure
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*
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* Scroll the current message along the LCD by one character, rearming the
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* timer if required.
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*/
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static void img_ascii_lcd_scroll(struct timer_list *t)
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{
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struct img_ascii_lcd_ctx *ctx = from_timer(ctx, t, timer);
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unsigned int i, ch = ctx->scroll_pos;
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unsigned int num_chars = ctx->cfg->num_chars;
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/* update the current message string */
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for (i = 0; i < num_chars;) {
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/* copy as many characters from the string as possible */
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for (; i < num_chars && ch < ctx->message_len; i++, ch++)
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ctx->curr[i] = ctx->message[ch];
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/* wrap around to the start of the string */
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ch = 0;
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}
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/* update the LCD */
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ctx->cfg->update(ctx);
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/* move on to the next character */
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ctx->scroll_pos++;
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ctx->scroll_pos %= ctx->message_len;
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/* rearm the timer */
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if (ctx->message_len > ctx->cfg->num_chars)
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mod_timer(&ctx->timer, jiffies + ctx->scroll_rate);
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}
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/**
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* img_ascii_lcd_display() - set the message to be displayed
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* @ctx: pointer to the private data structure
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* @msg: the message to display
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* @count: length of msg, or -1
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*
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* Display a new message @msg on the LCD. @msg can be longer than the number of
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* characters the LCD can display, in which case it will begin scrolling across
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* the LCD display.
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*
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* Return: 0 on success, -ENOMEM on memory allocation failure
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*/
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static int img_ascii_lcd_display(struct img_ascii_lcd_ctx *ctx,
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const char *msg, ssize_t count)
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{
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char *new_msg;
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/* stop the scroll timer */
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del_timer_sync(&ctx->timer);
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if (count == -1)
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count = strlen(msg);
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/* if the string ends with a newline, trim it */
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if (msg[count - 1] == '\n')
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count--;
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new_msg = devm_kmalloc(&ctx->pdev->dev, count + 1, GFP_KERNEL);
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if (!new_msg)
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return -ENOMEM;
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memcpy(new_msg, msg, count);
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new_msg[count] = 0;
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if (ctx->message)
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devm_kfree(&ctx->pdev->dev, ctx->message);
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ctx->message = new_msg;
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ctx->message_len = count;
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ctx->scroll_pos = 0;
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/* update the LCD */
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img_ascii_lcd_scroll(&ctx->timer);
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return 0;
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}
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/**
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* message_show() - read message via sysfs
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* @dev: the LCD device
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* @attr: the LCD message attribute
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* @buf: the buffer to read the message into
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*
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* Read the current message being displayed or scrolled across the LCD display
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* into @buf, for reads from sysfs.
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*
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* Return: the number of characters written to @buf
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*/
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static ssize_t message_show(struct device *dev, struct device_attribute *attr,
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char *buf)
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{
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struct img_ascii_lcd_ctx *ctx = dev_get_drvdata(dev);
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return sprintf(buf, "%s\n", ctx->message);
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}
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/**
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* message_store() - write a new message via sysfs
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* @dev: the LCD device
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* @attr: the LCD message attribute
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* @buf: the buffer containing the new message
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* @count: the size of the message in @buf
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*
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* Write a new message to display or scroll across the LCD display from sysfs.
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*
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* Return: the size of the message on success, else -ERRNO
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*/
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static ssize_t message_store(struct device *dev, struct device_attribute *attr,
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const char *buf, size_t count)
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{
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struct img_ascii_lcd_ctx *ctx = dev_get_drvdata(dev);
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int err;
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err = img_ascii_lcd_display(ctx, buf, count);
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return err ?: count;
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}
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static DEVICE_ATTR_RW(message);
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/**
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* img_ascii_lcd_probe() - probe an LCD display device
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* @pdev: the LCD platform device
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*
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* Probe an LCD display device, ensuring that we have the required resources in
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* order to access the LCD & setting up private data as well as sysfs files.
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*
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* Return: 0 on success, else -ERRNO
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*/
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static int img_ascii_lcd_probe(struct platform_device *pdev)
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{
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const struct of_device_id *match;
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const struct img_ascii_lcd_config *cfg;
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struct img_ascii_lcd_ctx *ctx;
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struct resource *res;
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int err;
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match = of_match_device(img_ascii_lcd_matches, &pdev->dev);
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if (!match)
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return -ENODEV;
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cfg = match->data;
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ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx) + cfg->num_chars,
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GFP_KERNEL);
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if (!ctx)
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return -ENOMEM;
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if (cfg->external_regmap) {
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ctx->regmap = syscon_node_to_regmap(pdev->dev.parent->of_node);
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if (IS_ERR(ctx->regmap))
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return PTR_ERR(ctx->regmap);
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if (of_property_read_u32(pdev->dev.of_node, "offset",
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&ctx->offset))
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return -EINVAL;
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} else {
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res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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ctx->base = devm_ioremap_resource(&pdev->dev, res);
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if (IS_ERR(ctx->base))
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return PTR_ERR(ctx->base);
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}
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ctx->pdev = pdev;
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ctx->cfg = cfg;
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ctx->message = NULL;
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ctx->scroll_pos = 0;
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ctx->scroll_rate = HZ / 2;
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/* initialise a timer for scrolling the message */
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timer_setup(&ctx->timer, img_ascii_lcd_scroll, 0);
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platform_set_drvdata(pdev, ctx);
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/* display a default message */
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err = img_ascii_lcd_display(ctx, "Linux " UTS_RELEASE " ", -1);
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if (err)
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goto out_del_timer;
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err = device_create_file(&pdev->dev, &dev_attr_message);
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if (err)
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goto out_del_timer;
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return 0;
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out_del_timer:
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del_timer_sync(&ctx->timer);
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return err;
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}
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/**
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* img_ascii_lcd_remove() - remove an LCD display device
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* @pdev: the LCD platform device
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*
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* Remove an LCD display device, freeing private resources & ensuring that the
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* driver stops using the LCD display registers.
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*
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* Return: 0
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*/
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static int img_ascii_lcd_remove(struct platform_device *pdev)
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{
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struct img_ascii_lcd_ctx *ctx = platform_get_drvdata(pdev);
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device_remove_file(&pdev->dev, &dev_attr_message);
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del_timer_sync(&ctx->timer);
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return 0;
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}
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static struct platform_driver img_ascii_lcd_driver = {
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.driver = {
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.name = "img-ascii-lcd",
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.of_match_table = img_ascii_lcd_matches,
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},
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.probe = img_ascii_lcd_probe,
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.remove = img_ascii_lcd_remove,
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};
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module_platform_driver(img_ascii_lcd_driver);
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MODULE_DESCRIPTION("Imagination Technologies ASCII LCD Display");
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MODULE_AUTHOR("Paul Burton <paul.burton@mips.com>");
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MODULE_LICENSE("GPL");
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