[ARM] 3405/1: lpd7a40x: CPLD ssp driver

Patch from Marc Singer

Driver for operating SSP devices through LPD7A40X CPLD chip.  This
driver is used by the audio codecs.

Signed-off-by: Marc Singer <elf@buici.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 343 insertions, 0 deletions

diff --git a/arch/arm/mach-lh7a40x/ssp-cpld.c b/arch/arm/mach-lh7a40x/ssp-cpld.c
new file mode 100644
index 000000000000..a10830186dac
--- /dev/null
+++ b/arch/arm/mach-lh7a40x/ssp-cpld.c
@@ -0,0 +1,343 @@
+/* arch/arm/mach-lh7a40x/ssp-cpld.c
+ *
+ *  Copyright (C) 2004,2005 Marc Singer
+ *
+ *  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.
+ *
+ * SSP/SPI driver for the CardEngine CPLD.
+ *
+ */
+
+/* NOTES
+   -----
+
+   o *** This driver is cribbed from the 7952x implementation.
+	 Some comments may not apply.
+
+   o This driver contains sufficient logic to control either the
+     serial EEPROMs or the audio codec.  It is included in the kernel
+     to support the codec.  The EEPROMs are really the responsibility
+     of the boot loader and should probably be left alone.
+
+   o The code must be augmented to cope with multiple, simultaneous
+     clients.
+     o The audio codec writes to the codec chip whenever playback
+       starts.
+     o The touchscreen driver writes to the ads chip every time it
+       samples.
+     o The audio codec must write 16 bits, but the touch chip writes
+       are 8 bits long.
+     o We need to be able to keep these configurations separate while
+       simultaneously active.
+
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+//#include <linux/sched.h>
+#include <linux/errno.h>
+#include <linux/interrupt.h>
+//#include <linux/ioport.h>
+#include <linux/init.h>
+#include <linux/delay.h>
+#include <linux/spinlock.h>
+
+#include <asm/io.h>
+#include <asm/irq.h>
+#include <asm/hardware.h>
+
+#include <asm/arch/ssp.h>
+
+//#define TALK
+
+#if defined (TALK)
+#define PRINTK(f...)		printk (f)
+#else
+#define PRINTK(f...)		do {} while (0)
+#endif
+
+#if defined (CONFIG_ARCH_LH7A400)
+# define CPLD_SPID		__REGP16(CPLD06_VIRT) /* SPI data */
+# define CPLD_SPIC		__REGP16(CPLD08_VIRT) /* SPI control */
+# define CPLD_SPIC_CS_CODEC	(1<<0)
+# define CPLD_SPIC_CS_TOUCH	(1<<1)
+# define CPLD_SPIC_WRITE	(0<<2)
+# define CPLD_SPIC_READ		(1<<2)
+# define CPLD_SPIC_DONE		(1<<3) /* r/o */
+# define CPLD_SPIC_LOAD		(1<<4)
+# define CPLD_SPIC_START	(1<<4)
+# define CPLD_SPIC_LOADED	(1<<5) /* r/o */
+#endif
+
+#define CPLD_SPI		__REGP16(CPLD0A_VIRT) /* SPI operation */
+#define CPLD_SPI_CS_EEPROM	(1<<3)
+#define CPLD_SPI_SCLK		(1<<2)
+#define CPLD_SPI_TX_SHIFT	(1)
+#define CPLD_SPI_TX		(1<<CPLD_SPI_TX_SHIFT)
+#define CPLD_SPI_RX_SHIFT	(0)
+#define CPLD_SPI_RX		(1<<CPLD_SPI_RX_SHIFT)
+
+/* *** FIXME: these timing values are substantially larger than the
+   *** chip requires. We may implement an nsleep () function. */
+#define T_SKH	1		/* Clock time high (us) */
+#define T_SKL	1		/* Clock time low (us) */
+#define T_CS	1		/* Minimum chip select low time (us)  */
+#define T_CSS	1		/* Minimum chip select setup time (us)  */
+#define T_DIS	1		/* Data setup time (us) */
+
+	 /* EEPROM SPI bits */
+#define P_START		(1<<9)
+#define P_WRITE		(1<<7)
+#define P_READ		(2<<7)
+#define P_ERASE		(3<<7)
+#define P_EWDS		(0<<7)
+#define P_WRAL		(0<<7)
+#define P_ERAL		(0<<7)
+#define P_EWEN		(0<<7)
+#define P_A_EWDS	(0<<5)
+#define P_A_WRAL	(1<<5)
+#define P_A_ERAL	(2<<5)
+#define P_A_EWEN	(3<<5)
+
+struct ssp_configuration {
+	int device;
+	int mode;
+	int speed;
+	int frame_size_write;
+	int frame_size_read;
+};
+
+static struct ssp_configuration ssp_configuration;
+static spinlock_t ssp_lock;
+
+static void enable_cs (void)
+{
+	switch (ssp_configuration.device) {
+	case DEVICE_EEPROM:
+		CPLD_SPI |= CPLD_SPI_CS_EEPROM;
+		break;
+	}
+	udelay (T_CSS);
+}
+
+static void disable_cs (void)
+{
+	switch (ssp_configuration.device) {
+	case DEVICE_EEPROM:
+		CPLD_SPI &= ~CPLD_SPI_CS_EEPROM;
+		break;
+	}
+	udelay (T_CS);
+}
+
+static void pulse_clock (void)
+{
+	CPLD_SPI |=  CPLD_SPI_SCLK;
+	udelay (T_SKH);
+	CPLD_SPI &= ~CPLD_SPI_SCLK;
+	udelay (T_SKL);
+}
+
+
+/* execute_spi_command
+
+   sends an spi command to a device.  It first sends cwrite bits from
+   v.  If cread is greater than zero it will read cread bits
+   (discarding the leading 0 bit) and return them.  If cread is less
+   than zero it will check for completetion status and return 0 on
+   success or -1 on timeout.  If cread is zero it does nothing other
+   than sending the command.
+
+   On the LPD7A400, we can only read or write multiples of 8 bits on
+   the codec and the touch screen device.  Here, we round up.
+
+*/
+
+static int execute_spi_command (int v, int cwrite, int cread)
+{
+	unsigned long l = 0;
+
+#if defined (CONFIG_MACH_LPD7A400)
+	/* The codec and touch devices cannot be bit-banged.  Instead,
+	 * the CPLD provides an eight-bit shift register and a crude
+	 * interface.  */
+	if (   ssp_configuration.device == DEVICE_CODEC
+	    || ssp_configuration.device == DEVICE_TOUCH) {
+		int select = 0;
+
+		PRINTK ("spi(%d %d.%d) 0x%04x",
+			ssp_configuration.device, cwrite, cread,
+			v);
+#if defined (TALK)
+		if (ssp_configuration.device == DEVICE_CODEC)
+			PRINTK (" 0x%03x -> %2d", v & 0x1ff, (v >> 9) & 0x7f);
+#endif
+		PRINTK ("\n");
+
+		if (ssp_configuration.device == DEVICE_CODEC)
+			select = CPLD_SPIC_CS_CODEC;
+		if (ssp_configuration.device == DEVICE_TOUCH)
+			select = CPLD_SPIC_CS_TOUCH;
+		if (cwrite) {
+			for (cwrite = (cwrite + 7)/8; cwrite-- > 0; ) {
+				CPLD_SPID = (v >> (8*cwrite)) & 0xff;
+				CPLD_SPIC = select | CPLD_SPIC_LOAD;
+				while (!(CPLD_SPIC & CPLD_SPIC_LOADED))
+					;
+				CPLD_SPIC = select;
+				while (!(CPLD_SPIC & CPLD_SPIC_DONE))
+					;
+			}
+			v = 0;
+		}
+		if (cread) {
+			mdelay (2);	/* *** FIXME: required by ads7843? */
+			v = 0;
+			for (cread = (cread + 7)/8; cread-- > 0;) {
+				CPLD_SPID = 0;
+				CPLD_SPIC = select | CPLD_SPIC_READ
+					| CPLD_SPIC_START;
+				while (!(CPLD_SPIC & CPLD_SPIC_LOADED))
+					;
+				CPLD_SPIC = select | CPLD_SPIC_READ;
+				while (!(CPLD_SPIC & CPLD_SPIC_DONE))
+					;
+				v = (v << 8) | CPLD_SPID;
+			}
+		}
+		return v;
+	}
+#endif
+
+	PRINTK ("spi(%d) 0x%04x -> 0x%x\r\n", ssp_configuration.device,
+		v & 0x1ff, (v >> 9) & 0x7f);
+
+	enable_cs ();
+
+	v <<= CPLD_SPI_TX_SHIFT; /* Correction for position of SPI_TX bit */
+	while (cwrite--) {
+		CPLD_SPI
+			= (CPLD_SPI & ~CPLD_SPI_TX)
+			| ((v >> cwrite) & CPLD_SPI_TX);
+		udelay (T_DIS);
+		pulse_clock ();
+	}
+
+	if (cread < 0) {
+		int delay = 10;
+		disable_cs ();
+		udelay (1);
+		enable_cs ();
+
+		l = -1;
+		do {
+			if (CPLD_SPI & CPLD_SPI_RX) {
+				l = 0;
+				break;
+			}
+		} while (udelay (1), --delay);
+	}
+	else
+	/* We pulse the clock before the data to skip the leading zero. */
+		while (cread-- > 0) {
+			pulse_clock ();
+			l = (l<<1)
+				| (((CPLD_SPI & CPLD_SPI_RX)
+				    >> CPLD_SPI_RX_SHIFT) & 0x1);
+		}
+
+	disable_cs ();
+	return l;
+}
+
+static int ssp_init (void)
+{
+	spin_lock_init (&ssp_lock);
+	memset (&ssp_configuration, 0, sizeof (ssp_configuration));
+	return 0;
+}
+
+
+/* ssp_chip_select
+
+   drops the chip select line for the CPLD shift-register controlled
+   devices.  It doesn't enable chip
+
+*/
+
+static void ssp_chip_select (int enable)
+{
+#if defined (CONFIG_MACH_LPD7A400)
+	int select;
+
+	if (ssp_configuration.device == DEVICE_CODEC)
+		select = CPLD_SPIC_CS_CODEC;
+	else if (ssp_configuration.device == DEVICE_TOUCH)
+		select = CPLD_SPIC_CS_TOUCH;
+	else
+		return;
+
+	if (enable)
+		CPLD_SPIC = select;
+	else
+		CPLD_SPIC = 0;
+#endif
+}
+
+static void ssp_acquire (void)
+{
+	spin_lock (&ssp_lock);
+}
+
+static void ssp_release (void)
+{
+	ssp_chip_select (0);	/* just in case */
+	spin_unlock (&ssp_lock);
+}
+
+static int ssp_configure (int device, int mode, int speed,
+			   int frame_size_write, int frame_size_read)
+{
+	ssp_configuration.device		= device;
+	ssp_configuration.mode			= mode;
+	ssp_configuration.speed			= speed;
+	ssp_configuration.frame_size_write	= frame_size_write;
+	ssp_configuration.frame_size_read	= frame_size_read;
+
+	return 0;
+}
+
+static int ssp_read (void)
+{
+	return execute_spi_command (0, 0, ssp_configuration.frame_size_read);
+}
+
+static int ssp_write (u16 data)
+{
+	execute_spi_command (data, ssp_configuration.frame_size_write, 0);
+	return 0;
+}
+
+static int ssp_write_read (u16 data)
+{
+	return execute_spi_command (data, ssp_configuration.frame_size_write,
+				    ssp_configuration.frame_size_read);
+}
+
+struct ssp_driver lh7a40x_cpld_ssp_driver = {
+	.init		= ssp_init,
+	.acquire	= ssp_acquire,
+	.release	= ssp_release,
+	.configure	= ssp_configure,
+	.chip_select	= ssp_chip_select,
+	.read		= ssp_read,
+	.write		= ssp_write,
+	.write_read	= ssp_write_read,
+};
+
+
+MODULE_AUTHOR("Marc Singer");
+MODULE_DESCRIPTION("LPD7A40X CPLD SPI driver");
+MODULE_LICENSE("GPL");