TI DaVinci: Driver for the davinci SPI controller

This adds a driver for the SPI controller found on davinci
based SoCs from Texas Instruments.

Signed-off-by: Sekhar Nori <nsekhar@ti.com>
Signed-off-by: Sudhakar Rajashekhara <sudhakar.raj@ti.com>
Signed-off-by: Sandeep Paulraj <s-paulraj@ti.com>

1 files changed, 223 insertions, 0 deletions

diff --git a/drivers/spi/davinci_spi.c b/drivers/spi/davinci_spi.c
new file mode 100644
index 0000000..ebc7f80
--- /dev/null
+++ b/drivers/spi/davinci_spi.c
@@ -0,0 +1,223 @@
+/*
+ * Copyright (C) 2009 Texas Instruments Incorporated - http://www.ti.com/
+ *
+ * Driver for SPI controller on DaVinci. Based on atmel_spi.c
+ * by Atmel Corporation
+ *
+ * Copyright (C) 2007 Atmel Corporation
+ *
+ * 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/arch/hardware.h>
+#include "davinci_spi.h"
+
+void spi_init()
+{
+	/* do nothing */
+}
+
+struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs,
+			unsigned int max_hz, unsigned int mode)
+{
+	struct davinci_spi_slave	*ds;
+
+	if (!spi_cs_is_valid(bus, cs))
+		return NULL;
+
+	ds = malloc(sizeof(*ds));
+	if (!ds)
+		return NULL;
+
+	ds->slave.bus = bus;
+	ds->slave.cs = cs;
+	ds->regs = (struct davinci_spi_regs *)CONFIG_SYS_SPI_BASE;
+	ds->freq = max_hz;
+
+	return &ds->slave;
+}
+
+void spi_free_slave(struct spi_slave *slave)
+{
+	struct davinci_spi_slave *ds = to_davinci_spi(slave);
+
+	free(ds);
+}
+
+int spi_claim_bus(struct spi_slave *slave)
+{
+	struct davinci_spi_slave *ds = to_davinci_spi(slave);
+	unsigned int scalar, data1_reg_val = 0;
+
+	/* Enable the SPI hardware */
+	writel(SPIGCR0_SPIRST_MASK, &ds->regs->gcr0);
+	udelay(1000);
+	writel(SPIGCR0_SPIENA_MASK, &ds->regs->gcr0);
+
+	/* Set master mode, powered up and not activated */
+	writel(SPIGCR1_MASTER_MASK | SPIGCR1_CLKMOD_MASK, &ds->regs->gcr1);
+
+	/* CS, CLK, SIMO and SOMI are functional pins */
+	writel((SPIPC0_EN0FUN_MASK | SPIPC0_CLKFUN_MASK |
+		SPIPC0_DOFUN_MASK | SPIPC0_DIFUN_MASK), &ds->regs->pc0);
+
+	/* setup format */
+	scalar = ((CONFIG_SYS_SPI_CLK / ds->freq) - 1) & 0xFF;
+
+	/*
+	 * Use following format:
+	 *   character length = 8,
+	 *   clock signal delayed by half clk cycle,
+	 *   clock low in idle state - Mode 0,
+	 *   MSB shifted out first
+	 */
+	writel(8 | (scalar << SPIFMT_PRESCALE_SHIFT) |
+		(1 << SPIFMT_PHASE_SHIFT), &ds->regs->fmt0);
+
+	/* hold cs active at end of transfer until explicitly de-asserted */
+	data1_reg_val = (1 << SPIDAT1_CSHOLD_SHIFT) |
+			(slave->cs << SPIDAT1_CSNR_SHIFT);
+	writel(data1_reg_val, &ds->regs->dat1);
+
+	/*
+	 * Including a minor delay. No science here. Should be good even with
+	 * no delay
+	 */
+	writel((50 << SPI_C2TDELAY_SHIFT) |
+		(50 << SPI_T2CDELAY_SHIFT), &ds->regs->delay);
+
+	/* default chip select register */
+	writel(SPIDEF_CSDEF0_MASK, &ds->regs->def);
+
+	/* no interrupts */
+	writel(0, &ds->regs->int0);
+	writel(0, &ds->regs->lvl);
+
+	/* enable SPI */
+	writel((readl(&ds->regs->gcr1) | SPIGCR1_SPIENA_MASK), &ds->regs->gcr1);
+
+	return 0;
+}
+
+void spi_release_bus(struct spi_slave *slave)
+{
+	struct davinci_spi_slave *ds = to_davinci_spi(slave);
+
+	/* Disable the SPI hardware */
+	writel(SPIGCR0_SPIRST_MASK, &ds->regs->gcr0);
+}
+
+int spi_xfer(struct spi_slave *slave, unsigned int bitlen,
+		const void *dout, void *din, unsigned long flags)
+{
+	struct davinci_spi_slave *ds = to_davinci_spi(slave);
+	unsigned int	len, data1_reg_val = readl(&ds->regs->dat1);
+	int		ret, i;
+	const u8	*txp = dout; /* dout can be NULL for read operation */
+	u8		*rxp = din;  /* din can be NULL for write operation */
+
+	ret = 0;
+
+	if (bitlen == 0)
+		/* Finish any previously submitted transfers */
+		goto out;
+
+	/*
+	 * It's not clear how non-8-bit-aligned transfers are supposed to be
+	 * represented as a stream of bytes...this is a limitation of
+	 * the current SPI interface - here we terminate on receiving such a
+	 * transfer request.
+	 */
+	if (bitlen % 8) {
+		/* Errors always terminate an ongoing transfer */
+		flags |= SPI_XFER_END;
+		goto out;
+	}
+
+	len = bitlen / 8;
+
+	/* do an empty read to clear the current contents */
+	readl(&ds->regs->buf);
+
+	/* keep writing and reading 1 byte until done */
+	for (i = 0; i < len; i++) {
+		/* wait till TXFULL is asserted */
+		while (readl(&ds->regs->buf) & SPIBUF_TXFULL_MASK);
+
+		/* write the data */
+		data1_reg_val &= ~0xFFFF;
+		if (txp) {
+			data1_reg_val |= *txp;
+			txp++;
+		}
+
+		/*
+		 * Write to DAT1 is required to keep the serial transfer going.
+		 * We just terminate when we reach the end.
+		 */
+		if ((i == (len - 1)) && (flags & SPI_XFER_END)) {
+			/* clear CS hold */
+			writel(data1_reg_val &
+				~(1 << SPIDAT1_CSHOLD_SHIFT), &ds->regs->dat1);
+		} else {
+			/* enable CS hold */
+			data1_reg_val |= ((1 << SPIDAT1_CSHOLD_SHIFT) |
+					(slave->cs << SPIDAT1_CSNR_SHIFT));
+			writel(data1_reg_val, &ds->regs->dat1);
+		}
+
+		/* read the data - wait for data availability */
+		while (readl(&ds->regs->buf) & SPIBUF_RXEMPTY_MASK);
+
+		if (rxp) {
+			*rxp = readl(&ds->regs->buf) & 0xFF;
+			rxp++;
+		} else {
+			/* simply drop the read character */
+			readl(&ds->regs->buf);
+		}
+	}
+	return 0;
+
+out:
+	if (flags & SPI_XFER_END) {
+		writel(data1_reg_val &
+			~(1 << SPIDAT1_CSHOLD_SHIFT), &ds->regs->dat1);
+	}
+	return 0;
+}
+
+int spi_cs_is_valid(unsigned int bus, unsigned int cs)
+{
+	return bus == 0 && cs == 0;
+}
+
+void spi_cs_activate(struct spi_slave *slave)
+{
+	/* do nothing */
+}
+
+void spi_cs_deactivate(struct spi_slave *slave)
+{
+	/* do nothing */
+}
+