[U-Boot] [PATCH v2 1/2] ppc4xx: Add 440EPx SPI driver

[Steven A. Falco]

This patch adds an SPI driver for the 440EPx processor.

Tested on Sequoia.

Signed-off-by: Steven A. Falco <sfalco at harris.com>
---

Regarding Ben's comments:

First, thanks for reviewing.  You gave me two different approaches to consider,
1) using in/out functions, and 2) using a structure.  So, for this version,
I've followed the style of the example you gave, using the structure approach.

This driver may be applicable to other 4xx chips, but after looking at
the 405gp and 440gp, neither have a SPI hw device.  So, I'm making this
one exclusive to the 440epx until someone else wants it on another
processor.  At that point, it can be adapted as needed.

Regarding Stefan's comments:

I've renamed the file, and cleaned up the nits.  Given that I've used
the structure approach, I believe the in/out calls are not applicable.

Regarding Wolfgang's comments:

It is not for the fun of it.  We are planning a custom board which will
use the SPI port.  We are entering layout now, and the hardware won't
appear for at least a few months.  However, the Sequoia board does have
a connector for the SPI port, and I have connected a device to that connector
for prototyping purposes.  Other purchasers of the Sequoia may well have
a similar need.

You are certainly welcome to reject this driver if you feel that is
insufficient grounds for "usage".  Please let me know, so I don't bother
the list with it.

 drivers/spi/Makefile      |    1 +
 drivers/spi/ppc4xx_spi.c  |  119 +++++++++++++++++++++++++++++++++++++++++++++
 lude/asm-ppc/ppc4xx_spi.h |   62 +++++++++++++++++++++++
 3 files changed, 182 insertions(+), 0 deletions(-)
 create mode 100644 drivers/spi/ppc4xx_spi.c
 create mode 100644 include/asm-ppc/ppc4xx_spi.h

diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index 15e0f7a..7dbba5d 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -28,6 +28,7 @@ LIB	:= $(obj)libspi.a
 COBJS-$(CONFIG_ATMEL_SPI) += atmel_spi.o
 COBJS-$(CONFIG_MPC8XXX_SPI) += mpc8xxx_spi.o
 COBJS-$(CONFIG_MXC_SPI) += mxc_spi.o
+COBJS-$(CONFIG_PPC440EPX_SPI) += ppc4xx_spi.o
 COBJS-$(CONFIG_SOFT_SPI) += soft_spi.o
 
 COBJS	:= $(COBJS-y)
diff --git a/drivers/spi/ppc4xx_spi.c b/drivers/spi/ppc4xx_spi.c
new file mode 100644
index 0000000..156b056
--- /dev/null
+++ b/drivers/spi/ppc4xx_spi.c
@@ -0,0 +1,119 @@
+/*
+ * Copyright (C) 2008 Harris Corporation
+ * Author: Steven A. Falco <sfalco at harris.com>
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+#include <common.h>
+#include <spi.h>
+#include <malloc.h>
+
+#include <asm/io.h>
+#include <asm/ppc4xx_spi.h>
+
+void spi_init (void)
+{
+	volatile spi4xx_t *spi = (volatile spi4xx_t *) SPI_BASE_ADDR;
+
+	spi->cdm = 0;			/* Default to "go fast" */
+	spi->mode = SPI_MODE_SPE;	/* Enable port */
+}
+
+struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs,
+			unsigned int max_hz, unsigned int mode)
+{
+	volatile spi4xx_t *spi = (volatile spi4xx_t *) SPI_BASE_ADDR;
+
+	ulong opb = get_OPB_freq();
+	ulong divisor;
+	struct spi_slave *s;
+
+	if (!spi_cs_is_valid(bus, cs))
+		return NULL;
+
+	divisor = ((opb + (max_hz * 4) - 1) / (max_hz * 4)) - 1;
+	if (divisor > 255)
+		return NULL;
+
+	spi->cdm = divisor;
+
+	if (!(s = malloc(sizeof(struct spi_slave))))
+		return NULL;
+
+	if (mode & SPI_CPHA)
+		spi->mode &= ~SPI_MODE_SCP;
+	else
+		spi->mode |= SPI_MODE_SCP;
+
+	if (mode & SPI_CPOL)
+		spi->mode |= SPI_MODE_CI;
+	else
+		spi->mode &= ~SPI_MODE_CI;
+
+	s->bus = bus;
+	s->cs = cs;
+
+	return s;
+}
+
+void spi_free_slave(struct spi_slave *slave)
+{
+	free(slave);
+}
+
+int spi_claim_bus(struct spi_slave *slave)
+{
+	return 0;
+}
+
+void spi_release_bus(struct spi_slave *slave)
+{
+}
+
+#define GO	spi->cr = SPI_CR_STR
+#define TXWAIT	while(spi->sr & SPI_SR_BSY)
+#define RXWAIT	while(!(spi->sr & SPI_SR_RBR))
+
+int spi_xfer(struct spi_slave *slave, unsigned int bitlen,
+		const void *dout, void *din, unsigned long flags)
+{
+	volatile spi4xx_t *spi = (volatile spi4xx_t *) SPI_BASE_ADDR;
+
+	const u8 *txd = dout;
+	u8 *rxd = din;
+	int ii;
+
+	if (flags & SPI_XFER_BEGIN)
+		spi_cs_activate(slave);
+
+	/* Do a byte at a time */
+	for (ii = 0; ii < ((bitlen + 7) / 8); ii++) {
+		TXWAIT;
+		spi->txd = *txd++;
+		GO;
+		RXWAIT;
+		*rxd++ = spi->rxd;
+	}
+
+	if (flags & SPI_XFER_END)
+		spi_cs_deactivate(slave);
+
+	return 0;
+}
diff --git a/include/asm-ppc/ppc4xx_spi.h b/include/asm-ppc/ppc4xx_spi.h
new file mode 100644
index 0000000..135c9e6
--- /dev/null
+++ b/include/asm-ppc/ppc4xx_spi.h
@@ -0,0 +1,62 @@
+/*
+ * Copyright (C) 2008 Harris Corporation
+ * Author: Steven A. Falco <sfalco at harris.com>
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+#ifndef _4xx_spi_h_
+#define _4xx_spi_h_
+
+#include <asm/types.h>
+
+#if defined(CONFIG_440EPX)
+#define SPI_BASE_ADDR	(CONFIG_SYS_PERIPHERAL_BASE + 0x00000900)
+#endif
+
+/* Bits in the command register */
+#define SPI_CR_STR	0x01
+
+/* Bits in the status register */
+#define SPI_SR_RBR	0x01
+#define SPI_SR_BSY	0x02
+
+/* Bits in the mode register */
+#define SPI_MODE_IL	0x01
+#define SPI_MODE_CI	0x02
+#define SPI_MODE_RD	0x04
+#define SPI_MODE_SPE	0x08
+#define SPI_MODE_SCP	0x10
+
+#if defined(CONFIG_440EPX) || \
+	defined(CONFIG_440GRX)
+
+typedef struct spi4xx {
+	u8 mode;	/* mode register */
+	u8 rxd;		/* receive register */
+	u8 txd;		/* transmit register */
+	u8 cr;		/* command register */
+	u8 sr;		/* status register */
+	u8 res0;	/* reserved */
+	u8 cdm;		/* clock divisor */
+} spi4xx_t;
+
+#endif
+
+#endif /* _4xx_spi_h_ */
-- 
1.6.0.2