text: /*
   * drivers/net/wan/slic_ds26522.c
   *
   * Copyright (C) 2016 Freescale Semiconductor, Inc.
   *
   * Author:Zhao Qiang<qiang.zhao@nxp.com>
   *
   * 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.
   */
  
  #include <linux/bitrev.h>
  #include <linux/module.h>
  #include <linux/device.h>
  #include <linux/kernel.h>
  #include <linux/sched.h>
  #include <linux/kthread.h>
  #include <linux/spi/spi.h>
  #include <linux/wait.h>
  #include <linux/param.h>
  #include <linux/delay.h>
  #include <linux/of.h>
  #include <linux/of_address.h>
  #include <linux/io.h>
  #include "slic_ds26522.h"
  
  #define DRV_NAME "ds26522"
  
  #define SLIC_TRANS_LEN 1
  #define SLIC_TWO_LEN 2
  #define SLIC_THREE_LEN 3
  
  static struct spi_device *g_spi;
  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Zhao Qiang<B45475@freescale.com>");
  
  /* the read/write format of address is
   * w/r|A13|A12|A11|A10|A9|A8|A7|A6|A5|A4|A3|A2|A1|A0|x
   */
  static void slic_write(struct spi_device *spi, u16 addr,
  		       u8 data)
  {
  	u8 temp[3];
  
  	addr = bitrev16(addr) >> 1;
  	data = bitrev8(data);
  	temp[0] = (u8)((addr >> 8) & 0x7f);
  	temp[1] = (u8)(addr & 0xfe);
  	temp[2] = data;
  
  	/* write spi addr and value */
  	spi_write(spi, &temp[0], SLIC_THREE_LEN);
  }
  
  static u8 slic_read(struct spi_device *spi, u16 addr)
  {
  	u8 temp[2];
  	u8 data;
  
  	addr = bitrev16(addr) >> 1;
  	temp[0] = (u8)(((addr >> 8) & 0x7f) | 0x80);
  	temp[1] = (u8)(addr & 0xfe);
  
  	spi_write_then_read(spi, &temp[0], SLIC_TWO_LEN, &data,
  			    SLIC_TRANS_LEN);
  
  	data = bitrev8(data);
  	return data;
  }
  
  static bool get_slic_product_code(struct spi_device *spi)
  {
  	u8 device_id;
  
  	device_id = slic_read(spi, DS26522_IDR_ADDR);
  	if ((device_id & 0xf8) == 0x68)
  		return true;
  	else
  		return false;
  }
  
  static void ds26522_e1_spec_config(struct spi_device *spi)
  {
  	/* Receive E1 Mode, Framer Disabled */
  	slic_write(spi, DS26522_RMMR_ADDR, DS26522_RMMR_E1);
  
  	/* Transmit E1 Mode, Framer Disable */
  	slic_write(spi, DS26522_TMMR_ADDR, DS26522_TMMR_E1);
  
  	/* Receive E1 Mode Framer Enable */
  	slic_write(spi, DS26522_RMMR_ADDR,
  		   slic_read(spi, DS26522_RMMR_ADDR) | DS26522_RMMR_FRM_EN);
  
  	/* Transmit E1 Mode Framer Enable */
  	slic_write(spi, DS26522_TMMR_ADDR,
  		   slic_read(spi, DS26522_TMMR_ADDR) | DS26522_TMMR_FRM_EN);
  
  	/* RCR1, receive E1 B8zs & ESF */
  	slic_write(spi, DS26522_RCR1_ADDR,
  		   DS26522_RCR1_E1_HDB3 | DS26522_RCR1_E1_CCS);
  
  	/* RSYSCLK=2.048MHz, RSYNC-Output */
  	slic_write(spi, DS26522_RIOCR_ADDR,
  		   DS26522_RIOCR_2048KHZ | DS26522_RIOCR_RSIO_OUT);
  
  	/* TCR1 Transmit E1 b8zs */
  	slic_write(spi, DS26522_TCR1_ADDR, DS26522_TCR1_TB8ZS);
  
  	/* TSYSCLK=2.048MHz, TSYNC-Output */
  	slic_write(spi, DS26522_TIOCR_ADDR,
  		   DS26522_TIOCR_2048KHZ | DS26522_TIOCR_TSIO_OUT);
  
  	/* Set E1TAF */
  	slic_write(spi, DS26522_E1TAF_ADDR, DS26522_E1TAF_DEFAULT);
  
  	/* Set E1TNAF register */
  	slic_write(spi, DS26522_E1TNAF_ADDR, DS26522_E1TNAF_DEFAULT);
  
  	/* Receive E1 Mode Framer Enable & init Done */
  	slic_write(spi, DS26522_RMMR_ADDR, slic_read(spi, DS26522_RMMR_ADDR) |
  		   DS26522_RMMR_INIT_DONE);
  
  	/* Transmit E1 Mode Framer Enable & init Done */
  	slic_write(spi, DS26522_TMMR_ADDR, slic_read(spi, DS26522_TMMR_ADDR) |
  		   DS26522_TMMR_INIT_DONE);
  
  	/* Configure LIU E1 mode */
  	slic_write(spi, DS26522_LTRCR_ADDR, DS26522_LTRCR_E1);
  
  	/* E1 Mode default 75 ohm w/Transmit Impedance Matlinking */
  	slic_write(spi, DS26522_LTITSR_ADDR,
  		   DS26522_LTITSR_TLIS_75OHM | DS26522_LTITSR_LBOS_75OHM);
  
  	/* E1 Mode default 75 ohm Long Haul w/Receive Impedance Matlinking */
  	slic_write(spi, DS26522_LRISMR_ADDR,
  		   DS26522_LRISMR_75OHM | DS26522_LRISMR_MAX);
  
  	/* Enable Transmit output */
  	slic_write(spi, DS26522_LMCR_ADDR, DS26522_LMCR_TE);
  }
  
  static int slic_ds26522_init_configure(struct spi_device *spi)
  {
  	u16 addr;
  
  	/* set clock */
  	slic_write(spi, DS26522_GTCCR_ADDR, DS26522_GTCCR_BPREFSEL_REFCLKIN |
  			DS26522_GTCCR_BFREQSEL_2048KHZ |
  			DS26522_GTCCR_FREQSEL_2048KHZ);
  	slic_write(spi, DS26522_GTCR2_ADDR, DS26522_GTCR2_TSSYNCOUT);
  	slic_write(spi, DS26522_GFCR_ADDR, DS26522_GFCR_BPCLK_2048KHZ);
  
  	/* set gtcr */
  	slic_write(spi, DS26522_GTCR1_ADDR, DS26522_GTCR1);
  
  	/* Global LIU Software Reset Register */
  	slic_write(spi, DS26522_GLSRR_ADDR, DS26522_GLSRR_RESET);
  
  	/* Global Framer and BERT Software Reset Register */
  	slic_write(spi, DS26522_GFSRR_ADDR, DS26522_GFSRR_RESET);
  
  	usleep_range(100, 120);
  
  	slic_write(spi, DS26522_GLSRR_ADDR, DS26522_GLSRR_NORMAL);
  	slic_write(spi, DS26522_GFSRR_ADDR, DS26522_GFSRR_NORMAL);
  
  	/* Perform RX/TX SRESET,Reset receiver */
  	slic_write(spi, DS26522_RMMR_ADDR, DS26522_RMMR_SFTRST);
  
  	/* Reset tranceiver */
  	slic_write(spi, DS26522_TMMR_ADDR, DS26522_TMMR_SFTRST);
  
  	usleep_range(100, 120);
  
  	/* Zero all Framer Registers */
  	for (addr = DS26522_RF_ADDR_START; addr <= DS26522_RF_ADDR_END;
  	     addr++)
  		slic_write(spi, addr, 0);
  
  	for (addr = DS26522_TF_ADDR_START; addr <= DS26522_TF_ADDR_END;
  	     addr++)
  		slic_write(spi, addr, 0);
  
  	for (addr = DS26522_LIU_ADDR_START; addr <= DS26522_LIU_ADDR_END;
  	     addr++)
  		slic_write(spi, addr, 0);
  
  	for (addr = DS26522_BERT_ADDR_START; addr <= DS26522_BERT_ADDR_END;
  	     addr++)
  		slic_write(spi, addr, 0);
  
  	/* setup ds26522 for E1 specification */
  	ds26522_e1_spec_config(spi);
  
  	slic_write(spi, DS26522_GTCR1_ADDR, 0x00);
  
  	return 0;
  }
  
  static int slic_ds26522_remove(struct spi_device *spi)
  {
  	pr_info("DS26522 module uninstalled\n");
  	return 0;
  }
  
  static int slic_ds26522_probe(struct spi_device *spi)
  {
  	int ret = 0;
  
  	g_spi = spi;
  	spi->bits_per_word = 8;
  
  	if (!get_slic_product_code(spi))
  		return ret;
  
  	ret = slic_ds26522_init_configure(spi);
  	if (ret == 0)
  		pr_info("DS26522 cs%d configurated\n", spi->chip_select);
  
  	return ret;
  }
  
  static const struct spi_device_id slic_ds26522_id[] = {
  	{ .name = "ds26522" },
  	{ /* sentinel */ },
  };
  MODULE_DEVICE_TABLE(spi, slic_ds26522_id);
  
  static const struct of_device_id slic_ds26522_match[] = {
  	{
  	 .compatible = "maxim,ds26522",
  	 },
  	{},
  };
  MODULE_DEVICE_TABLE(of, slic_ds26522_match);
  
  static struct spi_driver slic_ds26522_driver = {
  	.driver = {
  		   .name = "ds26522",
  		   .bus = &spi_bus_type,
  		   .owner = THIS_MODULE,
  		   .of_match_table = slic_ds26522_match,
  		   },
  	.probe = slic_ds26522_probe,
  	.remove = slic_ds26522_remove,
  	.id_table = slic_ds26522_id,
  };
  
  static int __init slic_ds26522_init(void)
  {
  	return spi_register_driver(&slic_ds26522_driver);
  }
  
  static void __exit slic_ds26522_exit(void)
  {
  	spi_unregister_driver(&slic_ds26522_driver);
  }
  
  module_init(slic_ds26522_init);
  module_exit(slic_ds26522_exit);
  