203 lines
4.4 KiB
C
203 lines
4.4 KiB
C
/**
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* arch/arm/mac-sa1100/jornada720_ssp.c
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*
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* Copyright (C) 2006/2007 Kristoffer Ericson <Kristoffer.Ericson@gmail.com>
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* Copyright (C) 2006 Filip Zyzniewski <filip.zyzniewski@tefnet.pl>
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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 terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* SSP driver for the HP Jornada 710/720/728
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*/
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#include <linux/delay.h>
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#include <linux/errno.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/platform_device.h>
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#include <linux/sched.h>
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#include <linux/io.h>
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#include <mach/hardware.h>
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#include <mach/jornada720.h>
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#include <asm/hardware/ssp.h>
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static DEFINE_SPINLOCK(jornada_ssp_lock);
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static unsigned long jornada_ssp_flags;
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/**
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* jornada_ssp_reverse - reverses input byte
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*
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* we need to reverse all data we receive from the mcu due to its physical location
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* returns : 01110111 -> 11101110
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*/
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u8 inline jornada_ssp_reverse(u8 byte)
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{
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return
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((0x80 & byte) >> 7) |
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((0x40 & byte) >> 5) |
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((0x20 & byte) >> 3) |
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((0x10 & byte) >> 1) |
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((0x08 & byte) << 1) |
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((0x04 & byte) << 3) |
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((0x02 & byte) << 5) |
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((0x01 & byte) << 7);
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};
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EXPORT_SYMBOL(jornada_ssp_reverse);
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/**
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* jornada_ssp_byte - waits for ready ssp bus and sends byte
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*
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* waits for fifo buffer to clear and then transmits, if it doesn't then we will
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* timeout after <timeout> rounds. Needs mcu running before its called.
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*
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* returns : %mcu output on success
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* : %-ETIMEDOUT on timeout
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*/
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int jornada_ssp_byte(u8 byte)
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{
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int timeout = 400000;
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u16 ret;
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while ((GPLR & GPIO_GPIO10)) {
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if (!--timeout) {
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printk(KERN_WARNING "SSP: timeout while waiting for transmit\n");
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return -ETIMEDOUT;
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}
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cpu_relax();
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}
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ret = jornada_ssp_reverse(byte) << 8;
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ssp_write_word(ret);
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ssp_read_word(&ret);
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return jornada_ssp_reverse(ret);
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};
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EXPORT_SYMBOL(jornada_ssp_byte);
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/**
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* jornada_ssp_inout - decide if input is command or trading byte
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*
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* returns : (jornada_ssp_byte(byte)) on success
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* : %-ETIMEDOUT on timeout failure
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*/
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int jornada_ssp_inout(u8 byte)
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{
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int ret, i;
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/* true means command byte */
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if (byte != TXDUMMY) {
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ret = jornada_ssp_byte(byte);
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/* Proper return to commands is TxDummy */
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if (ret != TXDUMMY) {
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for (i = 0; i < 256; i++)/* flushing bus */
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if (jornada_ssp_byte(TXDUMMY) == -1)
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break;
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return -ETIMEDOUT;
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}
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} else /* Exchange TxDummy for data */
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ret = jornada_ssp_byte(TXDUMMY);
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return ret;
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};
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EXPORT_SYMBOL(jornada_ssp_inout);
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/**
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* jornada_ssp_start - enable mcu
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*
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*/
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void jornada_ssp_start(void)
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{
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spin_lock_irqsave(&jornada_ssp_lock, jornada_ssp_flags);
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GPCR = GPIO_GPIO25;
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udelay(50);
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return;
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};
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EXPORT_SYMBOL(jornada_ssp_start);
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/**
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* jornada_ssp_end - disable mcu and turn off lock
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*
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*/
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void jornada_ssp_end(void)
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{
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GPSR = GPIO_GPIO25;
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spin_unlock_irqrestore(&jornada_ssp_lock, jornada_ssp_flags);
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return;
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};
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EXPORT_SYMBOL(jornada_ssp_end);
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static int jornada_ssp_probe(struct platform_device *dev)
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{
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int ret;
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GPSR = GPIO_GPIO25;
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ret = ssp_init();
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/* worked fine, lets not bother with anything else */
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if (!ret) {
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printk(KERN_INFO "SSP: device initialized with irq\n");
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return ret;
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}
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printk(KERN_WARNING "SSP: initialization failed, trying non-irq solution \n");
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/* init of Serial 4 port */
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Ser4MCCR0 = 0;
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Ser4SSCR0 = 0x0387;
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Ser4SSCR1 = 0x18;
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/* clear out any left over data */
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ssp_flush();
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/* enable MCU */
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jornada_ssp_start();
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/* see if return value makes sense */
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ret = jornada_ssp_inout(GETBRIGHTNESS);
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/* seems like it worked, just feed it with TxDummy to get rid of data */
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if (ret == TXDUMMY)
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jornada_ssp_inout(TXDUMMY);
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jornada_ssp_end();
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/* failed, lets just kill everything */
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if (ret == -ETIMEDOUT) {
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printk(KERN_WARNING "SSP: attempts failed, bailing\n");
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ssp_exit();
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return -ENODEV;
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}
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/* all fine */
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printk(KERN_INFO "SSP: device initialized\n");
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return 0;
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};
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static int jornada_ssp_remove(struct platform_device *dev)
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{
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/* Note that this doesn't actually remove the driver, since theres nothing to remove
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* It just makes sure everything is turned off */
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GPSR = GPIO_GPIO25;
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ssp_exit();
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return 0;
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};
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struct platform_driver jornadassp_driver = {
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.probe = jornada_ssp_probe,
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.remove = jornada_ssp_remove,
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.driver = {
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.name = "jornada_ssp",
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},
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};
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static int __init jornada_ssp_init(void)
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{
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return platform_driver_register(&jornadassp_driver);
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}
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module_init(jornada_ssp_init);
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