tegra2: spi: Add SPI driver for Tegra2 SOC

This driver supports SPI on Tegra2, running at 48MHz.

Signed-off-by: Tom Warren <twarren@nvidia.com>
Acked-by: Mike Frysinger <vapier@gentoo.org>

1 files changed, 265 insertions, 0 deletions

diff --git a/drivers/spi/tegra2_spi.c b/drivers/spi/tegra2_spi.c
new file mode 100644
index 0000000000..fdcad093cf
--- /dev/null
+++ b/drivers/spi/tegra2_spi.c
@@ -0,0 +1,265 @@
+/*
+ * Copyright (c) 2010-2011 NVIDIA Corporation
+ * With help from the mpc8xxx SPI driver
+ * With more help from omap3_spi SPI driver
+ *
+ * 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 <malloc.h>
+#include <spi.h>
+#include <asm/io.h>
+#include <asm/gpio.h>
+#include <asm/arch/clk_rst.h>
+#include <asm/arch/clock.h>
+#include <asm/arch/pinmux.h>
+#include <asm/arch/tegra2_spi.h>
+
+struct tegra_spi_slave {
+	struct spi_slave slave;
+	struct spi_tegra *regs;
+	unsigned int freq;
+	unsigned int mode;
+};
+
+static inline struct tegra_spi_slave *to_tegra_spi(struct spi_slave *slave)
+{
+	return container_of(slave, struct tegra_spi_slave, slave);
+}
+
+int spi_cs_is_valid(unsigned int bus, unsigned int cs)
+{
+	/* Tegra2 SPI-Flash - only 1 device ('bus/cs') */
+	if (bus != 0 || cs != 0)
+		return 0;
+	else
+		return 1;
+}
+
+struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs,
+		unsigned int max_hz, unsigned int mode)
+{
+	struct tegra_spi_slave *spi;
+
+	if (!spi_cs_is_valid(bus, cs)) {
+		printf("SPI error: unsupported bus %d / chip select %d\n",
+		       bus, cs);
+		return NULL;
+	}
+
+	if (max_hz > TEGRA2_SPI_MAX_FREQ) {
+		printf("SPI error: unsupported frequency %d Hz. Max frequency"
+			" is %d Hz\n", max_hz, TEGRA2_SPI_MAX_FREQ);
+		return NULL;
+	}
+
+	spi = malloc(sizeof(struct tegra_spi_slave));
+	if (!spi) {
+		printf("SPI error: malloc of SPI structure failed\n");
+		return NULL;
+	}
+	spi->slave.bus = bus;
+	spi->slave.cs = cs;
+	spi->freq = max_hz;
+	spi->regs = (struct spi_tegra *)TEGRA2_SPI_BASE;
+	spi->mode = mode;
+
+	return &spi->slave;
+}
+
+void spi_free_slave(struct spi_slave *slave)
+{
+	struct tegra_spi_slave *spi = to_tegra_spi(slave);
+
+	free(spi);
+}
+
+void spi_init(void)
+{
+	/* do nothing */
+}
+
+int spi_claim_bus(struct spi_slave *slave)
+{
+	struct tegra_spi_slave *spi = to_tegra_spi(slave);
+	struct spi_tegra *regs = spi->regs;
+	u32 reg;
+
+	/* Change SPI clock to correct frequency, PLLP_OUT0 source */
+	clock_start_periph_pll(PERIPH_ID_SPI1, CLOCK_ID_PERIPH, spi->freq);
+
+	/* Clear stale status here */
+	reg = SPI_STAT_RDY | SPI_STAT_RXF_FLUSH | SPI_STAT_TXF_FLUSH | \
+		SPI_STAT_RXF_UNR | SPI_STAT_TXF_OVF;
+	writel(reg, &regs->status);
+	debug("spi_init: STATUS = %08x\n", readl(&regs->status));
+
+	/*
+	 * Use sw-controlled CS, so we can clock in data after ReadID, etc.
+	 */
+	reg = (spi->mode & 1) << SPI_CMD_ACTIVE_SDA_SHIFT;
+	if (spi->mode & 2)
+		reg |= 1 << SPI_CMD_ACTIVE_SCLK_SHIFT;
+	clrsetbits_le32(&regs->command, SPI_CMD_ACTIVE_SCLK_MASK |
+		SPI_CMD_ACTIVE_SDA_MASK, SPI_CMD_CS_SOFT | reg);
+	debug("spi_init: COMMAND = %08x\n", readl(&regs->command));
+
+	/*
+	 * SPI pins on Tegra2 are muxed - change pinmux later due to UART
+	 * issue.
+	 */
+	pinmux_set_func(PINGRP_GMD, PMUX_FUNC_SFLASH);
+	pinmux_tristate_disable(PINGRP_LSPI);
+	return 0;
+}
+
+void spi_release_bus(struct spi_slave *slave)
+{
+	/*
+	 * We can't release UART_DISABLE and set pinmux to UART4 here since
+	 * some code (e,g, spi_flash_probe) uses printf() while the SPI
+	 * bus is held. That is arguably bad, but it has the advantage of
+	 * already being in the source tree.
+	 */
+}
+
+void spi_cs_activate(struct spi_slave *slave)
+{
+	struct tegra_spi_slave *spi = to_tegra_spi(slave);
+
+	/* CS is negated on Tegra, so drive a 1 to get a 0 */
+	setbits_le32(&spi->regs->command, SPI_CMD_CS_VAL);
+}
+
+void spi_cs_deactivate(struct spi_slave *slave)
+{
+	struct tegra_spi_slave *spi = to_tegra_spi(slave);
+
+	/* CS is negated on Tegra, so drive a 0 to get a 1 */
+	clrbits_le32(&spi->regs->command, SPI_CMD_CS_VAL);
+}
+
+int spi_xfer(struct spi_slave *slave, unsigned int bitlen,
+		const void *data_out, void *data_in, unsigned long flags)
+{
+	struct tegra_spi_slave *spi = to_tegra_spi(slave);
+	struct spi_tegra *regs = spi->regs;
+	u32 reg, tmpdout, tmpdin = 0;
+	const u8 *dout = data_out;
+	u8 *din = data_in;
+	int num_bytes;
+	int ret;
+
+	debug("spi_xfer: slave %u:%u dout %08X din %08X bitlen %u\n",
+	      slave->bus, slave->cs, *(u8 *)dout, *(u8 *)din, bitlen);
+	if (bitlen % 8)
+		return -1;
+	num_bytes = bitlen / 8;
+
+	ret = 0;
+
+	reg = readl(&regs->status);
+	writel(reg, &regs->status);	/* Clear all SPI events via R/W */
+	debug("spi_xfer entry: STATUS = %08x\n", reg);
+
+	reg = readl(&regs->command);
+	reg |= SPI_CMD_TXEN | SPI_CMD_RXEN;
+	writel(reg, &regs->command);
+	debug("spi_xfer: COMMAND = %08x\n", readl(&regs->command));
+
+	if (flags & SPI_XFER_BEGIN)
+		spi_cs_activate(slave);
+
+	/* handle data in 32-bit chunks */
+	while (num_bytes > 0) {
+		int bytes;
+		int is_read = 0;
+		int tm, i;
+
+		tmpdout = 0;
+		bytes = (num_bytes > 4) ?  4 : num_bytes;
+
+		if (dout != NULL) {
+			for (i = 0; i < bytes; ++i)
+				tmpdout = (tmpdout << 8) | dout[i];
+		}
+
+		num_bytes -= bytes;
+		if (dout)
+			dout += bytes;
+
+		clrsetbits_le32(&regs->command, SPI_CMD_BIT_LENGTH_MASK,
+				bytes * 8 - 1);
+		writel(tmpdout, &regs->tx_fifo);
+		setbits_le32(&regs->command, SPI_CMD_GO);
+
+		/*
+		 * Wait for SPI transmit FIFO to empty, or to time out.
+		 * The RX FIFO status will be read and cleared last
+		 */
+		for (tm = 0, is_read = 0; tm < SPI_TIMEOUT; ++tm) {
+			u32 status;
+
+			status = readl(&regs->status);
+
+			/* We can exit when we've had both RX and TX activity */
+			if (is_read && (status & SPI_STAT_TXF_EMPTY))
+				break;
+
+			if ((status & (SPI_STAT_BSY | SPI_STAT_RDY)) !=
+					SPI_STAT_RDY)
+				tm++;
+
+			else if (!(status & SPI_STAT_RXF_EMPTY)) {
+				tmpdin = readl(&regs->rx_fifo);
+				is_read = 1;
+
+				/* swap bytes read in */
+				if (din != NULL) {
+					for (i = bytes - 1; i >= 0; --i) {
+						din[i] = tmpdin & 0xff;
+						tmpdin >>= 8;
+					}
+					din += bytes;
+				}
+			}
+		}
+
+		if (tm >= SPI_TIMEOUT)
+			ret = tm;
+
+		/* clear ACK RDY, etc. bits */
+		writel(readl(&regs->status), &regs->status);
+	}
+
+	if (flags & SPI_XFER_END)
+		spi_cs_deactivate(slave);
+
+	debug("spi_xfer: transfer ended. Value=%08x, status = %08x\n",
+		tmpdin, readl(&regs->status));
+
+	if (ret) {
+		printf("spi_xfer: timeout during SPI transfer, tm %d\n", ret);
+		return -1;
+	}
+
+	return 0;
+}