[ARM PATCH] 2085/1: PXA SSP driver

Patch from Liam Girdwood

This patch adds support the PXA250, 255, 26x and 27x SSP ports. It
provides a generic core for simple IO-based SSP applications and allows
easy port setup for DMA access.

Depends on register definitions in patch 2084/1

Signed-off-by: Liam Girdwood 

arch/arm/mach-pxa/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>
+ *
+ *  Revision history:
+ *   22nd Aug 2003 Initial version.
+ *
+ */
+
+#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 <asm/io.h>
+#include <asm/irq.h>
+#include <asm/hardware.h>
+#include <asm/arch/ssp.h>
+#include <asm/arch/pxa-regs.h>
+
+static irqreturn_t ssp_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+{
+	struct ssp_dev *dev = (struct ssp_dev*) dev_id;
+	unsigned int status = SSSR_P(dev->port);
+
+	SSSR_P(dev->port) = status; /* clear status bits */
+
+	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 (for future)
+ *   0			success
+ */
+int ssp_write_word(struct ssp_dev *dev, u32 data)
+{
+	while (!(SSSR_P(dev->port) & SSSR_TNF))
+		cpu_relax();
+
+	SSDR_P(dev->port) = data;
+
+	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 (for future)
+ *   32-bit data	success
+ */
+int ssp_read_word(struct ssp_dev *dev)
+{
+	while (!(SSSR_P(dev->port) & SSSR_RNE))
+		cpu_relax();
+
+	return SSDR_P(dev->port);
+}
+
+/**
+ * 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.
+ */
+void ssp_flush(struct ssp_dev *dev)
+{
+	do {
+		while (SSSR_P(dev->port) & SSSR_RNE) {
+			(void) SSDR_P(dev->port);
+		}
+	} while (SSSR_P(dev->port) & SSSR_BSY);
+}
+
+/**
+ * ssp_enable - enable the SSP port
+ *
+ * Turn on the SSP port.
+ */
+void ssp_enable(struct ssp_dev *dev)
+{
+	SSCR0_P(dev->port) |= SSCR0_SSE;
+}
+
+/**
+ * ssp_disable - shut down the SSP port
+ *
+ * Turn off the SSP port, optionally powering it down.
+ */
+void ssp_disable(struct ssp_dev *dev)
+{
+	SSCR0_P(dev->port) &= ~SSCR0_SSE;
+}
+
+/**
+ * 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 *ssp)
+{
+	ssp->cr0 = SSCR0_P(dev->port);
+	ssp->cr1 = SSCR1_P(dev->port);
+	ssp->to = SSTO_P(dev->port);
+	ssp->psp = SSPSP_P(dev->port);
+
+	SSCR0_P(dev->port) &= ~SSCR0_SSE;
+}
+
+/**
+ * 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 *ssp)
+{
+	SSSR_P(dev->port) = SSSR_ROR | SSSR_TUR | SSSR_BCE;
+
+	SSCR0_P(dev->port) = ssp->cr0 & ~SSCR0_SSE;
+	SSCR1_P(dev->port) = ssp->cr1;
+	SSTO_P(dev->port) = ssp->to;
+	SSPSP_P(dev->port) = ssp->psp;
+
+	SSCR0_P(dev->port) = ssp->cr0;
+}
+
+/**
+ * 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 mode, u32 flags, u32 psp_flags,
+						u32 speed)
+{
+	int ret, irq;
+
+	if (!request_mem_region(__PREG(SSCR0_P(dev->port)), 0x2c, "SSP")) {
+		return -EBUSY;
+	}
+
+	switch (port) {
+		case 1:
+			irq = IRQ_SSP;
+			break;
+#if defined (CONFIG_PXA27x)
+		case 2:
+			irq = IRQ_SSP2;
+			break;
+		case 3:
+			irq = IRQ_SSP3;
+			break;
+#else
+		case 2:
+			irq = IRQ_NSSP;
+			break;
+		case 3:
+			irq = IRQ_ASSP;
+			break;
+#endif
+		default:
+			return -ENODEV;
+	}
+
+	dev->port = port;
+	dev->mode = mode;
+	dev->flags = flags;
+	dev->psp_flags = psp_flags;
+	dev->speed = speed;
+
+	/* set up port type, speed, port settings */
+	SSCR0_P(dev->port) = (dev->speed | dev->mode);
+	SSCR1_P(dev->port) = dev->flags;
+	SSPSP_P(dev->port) = dev->psp_flags;
+
+	ret = request_irq(irq, ssp_interrupt, 0, "SSP", dev);
+	if (ret)
+		goto out_region;
+
+	/* turn on SSP port clock */
+	switch (dev->port) {
+#if defined (CONFIG_PXA27x)
+		case 1:
+			pxa_set_cken(CKEN23_SSP1, 1);
+			break;
+		case 2:
+			pxa_set_cken(CKEN3_SSP2, 1);
+			break;
+		case 3:
+			pxa_set_cken(CKEN4_SSP3, 1);
+			break;
+#else
+		case 1:
+			pxa_set_cken(CKEN3_SSP, 1);
+			break;
+		case 2:
+			pxa_set_cken(CKEN9_NSSP, 1);
+			break;
+		case 3:
+			pxa_set_cken(CKEN10_ASSP, 1);
+			break;
+#endif
+	}
+
+	return 0;
+
+out_region:
+	release_mem_region(__PREG(SSCR0_P(dev->port)), 0x2c);
+	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)
+{
+	int irq;
+
+	SSCR0_P(dev->port) &= ~SSCR0_SSE;
+
+	/* find irq, save power and turn off SSP port clock */
+	switch (dev->port) {
+#if defined (CONFIG_PXA27x)
+		case 1:
+			irq = IRQ_SSP;
+			pxa_set_cken(CKEN23_SSP1, 0);
+			break;
+		case 2:
+			irq = IRQ_SSP2;
+			pxa_set_cken(CKEN3_SSP2, 0);
+			break;
+		case 3:
+			irq = IRQ_SSP3;
+			pxa_set_cken(CKEN4_SSP3, 0);
+			break;
+#else
+		case 1:
+			irq = IRQ_SSP;
+			pxa_set_cken(CKEN3_SSP, 0);
+			break;
+		case 2:
+			irq = IRQ_NSSP;
+			pxa_set_cken(CKEN9_NSSP, 0);
+			break;
+		case 3:
+			irq = IRQ_ASSP;
+			pxa_set_cken(CKEN10_ASSP, 0);
+			break;
+#endif
+		default:
+			printk(KERN_WARNING "SSP: tried to close invalid port\n");
+			return;
+	}
+
+	free_irq(irq, dev);
+	release_mem_region(__PREG(SSCR0_P(dev->port)), 0x2c);
+}
+
+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);

include/asm-arm/arch-pxa/ssp.h

+/*
+ *  ssp.h
+ *
+ *  Copyright (C) 2003 Russell King, All Rights Reserved.
+ *
+ * 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.
+ *
+ * This driver supports the following PXA CPU/SSP ports:-
+ *
+ *       PXA250     SSP
+ *       PXA255     SSP, NSSP
+ *       PXA26x     SSP, NSSP, ASSP
+ *       PXA27x     SSP1, SSP2, SSP3
+ */
+
+#ifndef SSP_H
+#define SSP_H
+
+struct ssp_state {
+	u32	cr0;
+	u32 cr1;
+	u32 to;
+	u32 psp;
+};
+
+struct ssp_dev {
+	u32 port;
+	u32 mode;
+	u32 flags;
+	u32 psp_flags;
+	u32 speed;
+};
+
+int ssp_write_word(struct ssp_dev *dev, u32 data);
+int ssp_read_word(struct ssp_dev *dev);
+void ssp_flush(struct ssp_dev *dev);
+void ssp_enable(struct ssp_dev *dev);
+void ssp_disable(struct ssp_dev *dev);
+void ssp_save_state(struct ssp_dev *dev, struct ssp_state *ssp);
+void ssp_restore_state(struct ssp_dev *dev, struct ssp_state *ssp);
+int ssp_init(struct ssp_dev *dev, u32 port, u32 mode, u32 flags, u32 psp_flags,
+						u32 speed);
+void ssp_exit(struct ssp_dev *dev);
+
+#endif