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ssp.c

/*
 *  linux/arch/arm/mach-pxa/ssp.c
 *
 *  based on linux/arch/arm/mach-sa1100/ssp.c by Russell King
 *
 *  Copyright (C) 2003 Russell King.
 *  Copyright (C) 2003 Wolfson Microelectronics PLC
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 *  PXA2xx SSP driver.  This provides the generic core for simple
 *  IO-based SSP applications and allows easy port setup for DMA access.
 *
 *  Author: Liam Girdwood <liam.girdwood@wolfsonmicro.com>
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/ioport.h>
#include <linux/init.h>
#include <linux/mutex.h>
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/platform_device.h>

#include <asm/io.h>
#include <asm/irq.h>
#include <mach/hardware.h>
#include <mach/ssp.h>
#include <mach/pxa-regs.h>
#include <mach/regs-ssp.h>

#define TIMEOUT 100000

static irqreturn_t ssp_interrupt(int irq, void *dev_id)
{
      struct ssp_dev *dev = dev_id;
      struct ssp_device *ssp = dev->ssp;
      unsigned int status;

      status = __raw_readl(ssp->mmio_base + SSSR);
      __raw_writel(status, ssp->mmio_base + SSSR);

      if (status & SSSR_ROR)
            printk(KERN_WARNING "SSP(%d): receiver overrun\n", dev->port);

      if (status & SSSR_TUR)
            printk(KERN_WARNING "SSP(%d): transmitter underrun\n", dev->port);

      if (status & SSSR_BCE)
            printk(KERN_WARNING "SSP(%d): bit count error\n", dev->port);

      return IRQ_HANDLED;
}

/**
 * ssp_write_word - write a word to the SSP port
 * @data: 32-bit, MSB justified data to write.
 *
 * Wait for a free entry in the SSP transmit FIFO, and write a data
 * word to the SSP port.
 *
 * The caller is expected to perform the necessary locking.
 *
 * Returns:
 *   %-ETIMEDOUT  timeout occurred
 *   0                  success
 */
int ssp_write_word(struct ssp_dev *dev, u32 data)
{
      struct ssp_device *ssp = dev->ssp;
      int timeout = TIMEOUT;

      while (!(__raw_readl(ssp->mmio_base + SSSR) & SSSR_TNF)) {
              if (!--timeout)
                  return -ETIMEDOUT;
            cpu_relax();
      }

      __raw_writel(data, ssp->mmio_base + SSDR);

      return 0;
}

/**
 * ssp_read_word - read a word from the SSP port
 *
 * Wait for a data word in the SSP receive FIFO, and return the
 * received data.  Data is LSB justified.
 *
 * Note: Currently, if data is not expected to be received, this
 * function will wait for ever.
 *
 * The caller is expected to perform the necessary locking.
 *
 * Returns:
 *   %-ETIMEDOUT  timeout occurred
 *   32-bit data  success
 */
int ssp_read_word(struct ssp_dev *dev, u32 *data)
{
      struct ssp_device *ssp = dev->ssp;
      int timeout = TIMEOUT;

      while (!(__raw_readl(ssp->mmio_base + SSSR) & SSSR_RNE)) {
              if (!--timeout)
                  return -ETIMEDOUT;
            cpu_relax();
      }

      *data = __raw_readl(ssp->mmio_base + SSDR);
      return 0;
}

/**
 * ssp_flush - flush the transmit and receive FIFOs
 *
 * Wait for the SSP to idle, and ensure that the receive FIFO
 * is empty.
 *
 * The caller is expected to perform the necessary locking.
 */
int ssp_flush(struct ssp_dev *dev)
{
      struct ssp_device *ssp = dev->ssp;
      int timeout = TIMEOUT * 2;

      /* ensure TX FIFO is empty instead of not full */
      if (cpu_is_pxa3xx()) {
            while (__raw_readl(ssp->mmio_base + SSSR) & 0xf00) {
                  if (!--timeout)
                        return -ETIMEDOUT;
                  cpu_relax();
            }
            timeout = TIMEOUT * 2;
      }

      do {
            while (__raw_readl(ssp->mmio_base + SSSR) & SSSR_RNE) {
                    if (!--timeout)
                        return -ETIMEDOUT;
                  (void)__raw_readl(ssp->mmio_base + SSDR);
            }
              if (!--timeout)
                  return -ETIMEDOUT;
      } while (__raw_readl(ssp->mmio_base + SSSR) & SSSR_BSY);

      return 0;
}

/**
 * ssp_enable - enable the SSP port
 *
 * Turn on the SSP port.
 */
void ssp_enable(struct ssp_dev *dev)
{
      struct ssp_device *ssp = dev->ssp;
      uint32_t sscr0;

      sscr0 = __raw_readl(ssp->mmio_base + SSCR0);
      sscr0 |= SSCR0_SSE;
      __raw_writel(sscr0, ssp->mmio_base + SSCR0);
}

/**
 * ssp_disable - shut down the SSP port
 *
 * Turn off the SSP port, optionally powering it down.
 */
void ssp_disable(struct ssp_dev *dev)
{
      struct ssp_device *ssp = dev->ssp;
      uint32_t sscr0;

      sscr0 = __raw_readl(ssp->mmio_base + SSCR0);
      sscr0 &= ~SSCR0_SSE;
      __raw_writel(sscr0, ssp->mmio_base + SSCR0);
}

/**
 * ssp_save_state - save the SSP configuration
 * @ssp: pointer to structure to save SSP configuration
 *
 * Save the configured SSP state for suspend.
 */
void ssp_save_state(struct ssp_dev *dev, struct ssp_state *state)
{
      struct ssp_device *ssp = dev->ssp;

      state->cr0 = __raw_readl(ssp->mmio_base + SSCR0);
      state->cr1 = __raw_readl(ssp->mmio_base + SSCR1);
      state->to  = __raw_readl(ssp->mmio_base + SSTO);
      state->psp = __raw_readl(ssp->mmio_base + SSPSP);

      ssp_disable(dev);
}

/**
 * ssp_restore_state - restore a previously saved SSP configuration
 * @ssp: pointer to configuration saved by ssp_save_state
 *
 * Restore the SSP configuration saved previously by ssp_save_state.
 */
void ssp_restore_state(struct ssp_dev *dev, struct ssp_state *state)
{
      struct ssp_device *ssp = dev->ssp;
      uint32_t sssr = SSSR_ROR | SSSR_TUR | SSSR_BCE;

      __raw_writel(sssr, ssp->mmio_base + SSSR);

      __raw_writel(state->cr0 & ~SSCR0_SSE, ssp->mmio_base + SSCR0);
      __raw_writel(state->cr1, ssp->mmio_base + SSCR1);
      __raw_writel(state->to,  ssp->mmio_base + SSTO);
      __raw_writel(state->psp, ssp->mmio_base + SSPSP);
      __raw_writel(state->cr0, ssp->mmio_base + SSCR0);
}

/**
 * ssp_config - configure SSP port settings
 * @mode: port operating mode
 * @flags: port config flags
 * @psp_flags: port PSP config flags
 * @speed: port speed
 *
 * Port MUST be disabled by ssp_disable before making any config changes.
 */
int ssp_config(struct ssp_dev *dev, u32 mode, u32 flags, u32 psp_flags, u32 speed)
{
      struct ssp_device *ssp = dev->ssp;

      dev->mode = mode;
      dev->flags = flags;
      dev->psp_flags = psp_flags;
      dev->speed = speed;

      /* set up port type, speed, port settings */
      __raw_writel((dev->speed | dev->mode), ssp->mmio_base + SSCR0);
      __raw_writel(dev->flags, ssp->mmio_base + SSCR1);
      __raw_writel(dev->psp_flags, ssp->mmio_base + SSPSP);

      return 0;
}

/**
 * ssp_init - setup the SSP port
 *
 * initialise and claim resources for the SSP port.
 *
 * Returns:
 *   %-ENODEV     if the SSP port is unavailable
 *   %-EBUSY      if the resources are already in use
 *   %0           on success
 */
int ssp_init(struct ssp_dev *dev, u32 port, u32 init_flags)
{
      struct ssp_device *ssp;
      int ret;

      ssp = ssp_request(port, "SSP");
      if (ssp == NULL)
            return -ENODEV;

      dev->ssp = ssp;
      dev->port = port;

      /* do we need to get irq */
      if (!(init_flags & SSP_NO_IRQ)) {
            ret = request_irq(ssp->irq, ssp_interrupt,
                        0, "SSP", dev);
            if (ret)
                  goto out_region;
            dev->irq = ssp->irq;
      } else
            dev->irq = NO_IRQ;

      /* turn on SSP port clock */
      clk_enable(ssp->clk);
      return 0;

out_region:
      ssp_free(ssp);
      return ret;
}

/**
 * ssp_exit - undo the effects of ssp_init
 *
 * release and free resources for the SSP port.
 */
void ssp_exit(struct ssp_dev *dev)
{
      struct ssp_device *ssp = dev->ssp;

      ssp_disable(dev);
      if (dev->irq != NO_IRQ)
            free_irq(dev->irq, dev);
      clk_disable(ssp->clk);
      ssp_free(ssp);
}

static DEFINE_MUTEX(ssp_lock);
static LIST_HEAD(ssp_list);

struct ssp_device *ssp_request(int port, const char *label)
{
      struct ssp_device *ssp = NULL;

      mutex_lock(&ssp_lock);

      list_for_each_entry(ssp, &ssp_list, node) {
            if (ssp->port_id == port && ssp->use_count == 0) {
                  ssp->use_count++;
                  ssp->label = label;
                  break;
            }
      }

      mutex_unlock(&ssp_lock);

      if (&ssp->node == &ssp_list)
            return NULL;

      return ssp;
}
EXPORT_SYMBOL(ssp_request);

void ssp_free(struct ssp_device *ssp)
{
      mutex_lock(&ssp_lock);
      if (ssp->use_count) {
            ssp->use_count--;
            ssp->label = NULL;
      } else
            dev_err(&ssp->pdev->dev, "device already free\n");
      mutex_unlock(&ssp_lock);
}
EXPORT_SYMBOL(ssp_free);

static int __devinit ssp_probe(struct platform_device *pdev, int type)
{
      struct resource *res;
      struct ssp_device *ssp;
      int ret = 0;

      ssp = kzalloc(sizeof(struct ssp_device), GFP_KERNEL);
      if (ssp == NULL) {
            dev_err(&pdev->dev, "failed to allocate memory");
            return -ENOMEM;
      }
      ssp->pdev = pdev;

      ssp->clk = clk_get(&pdev->dev, "SSPCLK");
      if (IS_ERR(ssp->clk)) {
            ret = PTR_ERR(ssp->clk);
            goto err_free;
      }

      res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
      if (res == NULL) {
            dev_err(&pdev->dev, "no memory resource defined\n");
            ret = -ENODEV;
            goto err_free_clk;
      }

      res = request_mem_region(res->start, res->end - res->start + 1,
                  pdev->name);
      if (res == NULL) {
            dev_err(&pdev->dev, "failed to request memory resource\n");
            ret = -EBUSY;
            goto err_free_clk;
      }

      ssp->phys_base = res->start;

      ssp->mmio_base = ioremap(res->start, res->end - res->start + 1);
      if (ssp->mmio_base == NULL) {
            dev_err(&pdev->dev, "failed to ioremap() registers\n");
            ret = -ENODEV;
            goto err_free_mem;
      }

      ssp->irq = platform_get_irq(pdev, 0);
      if (ssp->irq < 0) {
            dev_err(&pdev->dev, "no IRQ resource defined\n");
            ret = -ENODEV;
            goto err_free_io;
      }

      res = platform_get_resource(pdev, IORESOURCE_DMA, 0);
      if (res == NULL) {
            dev_err(&pdev->dev, "no SSP RX DRCMR defined\n");
            ret = -ENODEV;
            goto err_free_io;
      }
      ssp->drcmr_rx = res->start;

      res = platform_get_resource(pdev, IORESOURCE_DMA, 1);
      if (res == NULL) {
            dev_err(&pdev->dev, "no SSP TX DRCMR defined\n");
            ret = -ENODEV;
            goto err_free_io;
      }
      ssp->drcmr_tx = res->start;

      /* PXA2xx/3xx SSP ports starts from 1 and the internal pdev->id
       * starts from 0, do a translation here
       */
      ssp->port_id = pdev->id + 1;
      ssp->use_count = 0;
      ssp->type = type;

      mutex_lock(&ssp_lock);
      list_add(&ssp->node, &ssp_list);
      mutex_unlock(&ssp_lock);

      platform_set_drvdata(pdev, ssp);
      return 0;

err_free_io:
      iounmap(ssp->mmio_base);
err_free_mem:
      release_mem_region(res->start, res->end - res->start + 1);
err_free_clk:
      clk_put(ssp->clk);
err_free:
      kfree(ssp);
      return ret;
}

static int __devexit ssp_remove(struct platform_device *pdev)
{
      struct resource *res;
      struct ssp_device *ssp;

      ssp = platform_get_drvdata(pdev);
      if (ssp == NULL)
            return -ENODEV;

      iounmap(ssp->mmio_base);

      res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
      release_mem_region(res->start, res->end - res->start + 1);

      clk_put(ssp->clk);

      mutex_lock(&ssp_lock);
      list_del(&ssp->node);
      mutex_unlock(&ssp_lock);

      kfree(ssp);
      return 0;
}

static int __devinit pxa25x_ssp_probe(struct platform_device *pdev)
{
      return ssp_probe(pdev, PXA25x_SSP);
}

static int __devinit pxa25x_nssp_probe(struct platform_device *pdev)
{
      return ssp_probe(pdev, PXA25x_NSSP);
}

static int __devinit pxa27x_ssp_probe(struct platform_device *pdev)
{
      return ssp_probe(pdev, PXA27x_SSP);
}

static struct platform_driver pxa25x_ssp_driver = {
      .driver           = {
            .name = "pxa25x-ssp",
      },
      .probe            = pxa25x_ssp_probe,
      .remove           = __devexit_p(ssp_remove),
};

static struct platform_driver pxa25x_nssp_driver = {
      .driver           = {
            .name = "pxa25x-nssp",
      },
      .probe            = pxa25x_nssp_probe,
      .remove           = __devexit_p(ssp_remove),
};

static struct platform_driver pxa27x_ssp_driver = {
      .driver           = {
            .name = "pxa27x-ssp",
      },
      .probe            = pxa27x_ssp_probe,
      .remove           = __devexit_p(ssp_remove),
};

static int __init pxa_ssp_init(void)
{
      int ret = 0;

      ret = platform_driver_register(&pxa25x_ssp_driver);
      if (ret) {
            printk(KERN_ERR "failed to register pxa25x_ssp_driver");
            return ret;
      }

      ret = platform_driver_register(&pxa25x_nssp_driver);
      if (ret) {
            printk(KERN_ERR "failed to register pxa25x_nssp_driver");
            return ret;
      }

      ret = platform_driver_register(&pxa27x_ssp_driver);
      if (ret) {
            printk(KERN_ERR "failed to register pxa27x_ssp_driver");
            return ret;
      }

      return ret;
}

static void __exit pxa_ssp_exit(void)
{
      platform_driver_unregister(&pxa25x_ssp_driver);
      platform_driver_unregister(&pxa25x_nssp_driver);
      platform_driver_unregister(&pxa27x_ssp_driver);
}

arch_initcall(pxa_ssp_init);
module_exit(pxa_ssp_exit);

EXPORT_SYMBOL(ssp_write_word);
EXPORT_SYMBOL(ssp_read_word);
EXPORT_SYMBOL(ssp_flush);
EXPORT_SYMBOL(ssp_enable);
EXPORT_SYMBOL(ssp_disable);
EXPORT_SYMBOL(ssp_save_state);
EXPORT_SYMBOL(ssp_restore_state);
EXPORT_SYMBOL(ssp_init);
EXPORT_SYMBOL(ssp_exit);
EXPORT_SYMBOL(ssp_config);

MODULE_DESCRIPTION("PXA SSP driver");
MODULE_AUTHOR("Liam Girdwood");
MODULE_LICENSE("GPL");


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