tegra: add SPI SLINK driver

Add driver for tegra SPI "SLINK" style driver.  This controller is
similar to the tegra20 SPI "SFLASH" controller.  The difference is
that the SLINK controller is a genernal purpose SPI controller and the
SFLASH controller is special purpose and can only talk to FLASH
devices.  In addition there are potentially many instances of an SLINK
controller on tegra and only a single instance of SFLASH.  Tegra20 is
currently ths only version of tegra that instantiates an SFLASH
controller.

This driver supports basic PIO mode of operation and is configurable
(CONFIG_OF_CONTROL) to be driven off devicetree bindings.  Up to 4
devices per controller may be attached, although typically only a
single chip select line is exposed from tegra per controller so in
reality this is usually limited to 1.

To enable this driver, use CONFIG_TEGRA_SLINK

Signed-off-by: Allen Martin <amartin@nvidia.com>
Signed-off-by: Tom Warren <twarren@nvidia.com>

2 files changed, 344 insertions, 0 deletions

diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index 824d357..83abcbd 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -46,6 +46,7 @@ COBJS-$(CONFIG_SOFT_SPI) += soft_spi.o
 COBJS-$(CONFIG_SH_SPI) += sh_spi.o
 COBJS-$(CONFIG_FSL_ESPI) += fsl_espi.o
 COBJS-$(CONFIG_TEGRA_SPI) += tegra_spi.o
+COBJS-$(CONFIG_TEGRA_SLINK) += tegra_slink.o
 COBJS-$(CONFIG_XILINX_SPI) += xilinx_spi.o
 
 COBJS	:= $(COBJS-y)
diff --git a/drivers/spi/tegra_slink.c b/drivers/spi/tegra_slink.c
new file mode 100644
index 0000000..2c41fab
--- /dev/null
+++ b/drivers/spi/tegra_slink.c
@@ -0,0 +1,343 @@
+/*
+ * NVIDIA Tegra SPI-SLINK controller
+ *
+ * Copyright (c) 2010-2013 NVIDIA Corporation
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * 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 <asm/io.h>
+#include <asm/gpio.h>
+#include <asm/arch/clock.h>
+#include <asm/arch-tegra/clk_rst.h>
+#include <asm/arch-tegra/tegra_slink.h>
+#include <spi.h>
+#include <fdtdec.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+struct tegra_spi_ctrl {
+	struct slink_tegra *regs;
+	unsigned int freq;
+	unsigned int mode;
+	int periph_id;
+	int valid;
+};
+
+struct tegra_spi_slave {
+	struct spi_slave slave;
+	struct tegra_spi_ctrl *ctrl;
+};
+
+static struct tegra_spi_ctrl spi_ctrls[CONFIG_TEGRA_SLINK_CTRLS];
+
+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)
+{
+	if (bus >= CONFIG_TEGRA_SLINK_CTRLS || cs > 3 || !spi_ctrls[bus].valid)
+		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;
+
+	debug("%s: bus: %u, cs: %u, max_hz: %u, mode: %u\n", __func__,
+		bus, cs, max_hz, mode);
+
+	if (!spi_cs_is_valid(bus, cs)) {
+		printf("SPI error: unsupported bus %d / chip select %d\n",
+		       bus, cs);
+		return NULL;
+	}
+
+	if (max_hz > TEGRA_SPI_MAX_FREQ) {
+		printf("SPI error: unsupported frequency %d Hz. Max frequency"
+			" is %d Hz\n", max_hz, TEGRA_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->ctrl = &spi_ctrls[bus];
+	if (!spi->ctrl) {
+		printf("SPI error: could not find controller for bus %d\n",
+		       bus);
+		return NULL;
+	}
+
+	if (max_hz < spi->ctrl->freq) {
+		debug("%s: limiting frequency from %u to %u\n", __func__,
+		      spi->ctrl->freq, max_hz);
+		spi->ctrl->freq = max_hz;
+	}
+	spi->ctrl->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)
+{
+	struct tegra_spi_ctrl *ctrl;
+	int i;
+#ifdef CONFIG_OF_CONTROL
+	int node = 0;
+	int count;
+	int node_list[CONFIG_TEGRA_SLINK_CTRLS];
+
+	count = fdtdec_find_aliases_for_id(gd->fdt_blob, "spi",
+					   COMPAT_NVIDIA_TEGRA20_SLINK,
+					   node_list,
+					   CONFIG_TEGRA_SLINK_CTRLS);
+	for (i = 0; i < count; i++) {
+		ctrl = &spi_ctrls[i];
+		node = node_list[i];
+
+		ctrl->regs = (struct slink_tegra *)fdtdec_get_addr(gd->fdt_blob,
+								   node, "reg");
+		if ((fdt_addr_t)ctrl->regs == FDT_ADDR_T_NONE) {
+			debug("%s: no slink register found\n", __func__);
+			continue;
+		}
+		ctrl->freq = fdtdec_get_int(gd->fdt_blob, node,
+					    "spi-max-frequency", 0);
+		if (!ctrl->freq) {
+			debug("%s: no slink max frequency found\n", __func__);
+			continue;
+		}
+
+		ctrl->periph_id = clock_decode_periph_id(gd->fdt_blob, node);
+		if (ctrl->periph_id == PERIPH_ID_NONE) {
+			debug("%s: could not decode periph id\n", __func__);
+			continue;
+		}
+		ctrl->valid = 1;
+
+		debug("%s: found controller at %p, freq = %u, periph_id = %d\n",
+		      __func__, ctrl->regs, ctrl->freq, ctrl->periph_id);
+	}
+#else
+	for (i = 0; i < CONFIG_TEGRA_SLINK_CTRLS; i++) {
+		ctrl = &spi_ctrls[i];
+		u32 base_regs[] = {
+			NV_PA_SLINK1_BASE,
+			NV_PA_SLINK2_BASE,
+			NV_PA_SLINK3_BASE,
+			NV_PA_SLINK4_BASE,
+			NV_PA_SLINK5_BASE,
+			NV_PA_SLINK6_BASE,
+		};
+		int periph_ids[] = {
+			PERIPH_ID_SBC1,
+			PERIPH_ID_SBC2,
+			PERIPH_ID_SBC3,
+			PERIPH_ID_SBC4,
+			PERIPH_ID_SBC5,
+			PERIPH_ID_SBC6,
+		};
+		ctrl->regs = (struct slink_tegra *)base_regs[i];
+		ctrl->freq = TEGRA_SPI_MAX_FREQ;
+		ctrl->periph_id = periph_ids[i];
+		ctrl->valid = 1;
+
+		debug("%s: found controller at %p, freq = %u, periph_id = %d\n",
+		      __func__, ctrl->regs, ctrl->freq, ctrl->periph_id);
+	}
+#endif
+}
+
+int spi_claim_bus(struct spi_slave *slave)
+{
+	struct tegra_spi_slave *spi = to_tegra_spi(slave);
+	struct slink_tegra *regs = spi->ctrl->regs;
+	u32 reg;
+
+	/* Change SPI clock to correct frequency, PLLP_OUT0 source */
+	clock_start_periph_pll(spi->ctrl->periph_id, CLOCK_ID_PERIPH,
+			       spi->ctrl->freq);
+
+	/* Clear stale status here */
+	reg = SLINK_STAT_RDY | SLINK_STAT_RXF_FLUSH | SLINK_STAT_TXF_FLUSH | \
+		SLINK_STAT_RXF_UNR | SLINK_STAT_TXF_OVF;
+	writel(reg, &regs->status);
+	debug("%s: STATUS = %08x\n", __func__, readl(&regs->status));
+
+	/* Set master mode and sw controlled CS */
+	reg = readl(&regs->command);
+	reg |= SLINK_CMD_M_S | SLINK_CMD_CS_SOFT;
+	writel(reg, &regs->command);
+	debug("%s: COMMAND = %08x\n", __func__, readl(&regs->command));
+
+	return 0;
+}
+
+void spi_release_bus(struct spi_slave *slave)
+{
+}
+
+void spi_cs_activate(struct spi_slave *slave)
+{
+	struct tegra_spi_slave *spi = to_tegra_spi(slave);
+	struct slink_tegra *regs = spi->ctrl->regs;
+
+	/* CS is negated on Tegra, so drive a 1 to get a 0 */
+	setbits_le32(&regs->command, SLINK_CMD_CS_VAL);
+}
+
+void spi_cs_deactivate(struct spi_slave *slave)
+{
+	struct tegra_spi_slave *spi = to_tegra_spi(slave);
+	struct slink_tegra *regs = spi->ctrl->regs;
+
+	/* CS is negated on Tegra, so drive a 0 to get a 1 */
+	clrbits_le32(&regs->command, SLINK_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 slink_tegra *regs = spi->ctrl->regs;
+	u32 reg, tmpdout, tmpdin = 0;
+	const u8 *dout = data_out;
+	u8 *din = data_in;
+	int num_bytes;
+	int ret;
+
+	debug("%s: slave %u:%u dout %p din %p bitlen %u\n",
+	      __func__, slave->bus, slave->cs, dout, 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("%s entry: STATUS = %08x\n", __func__, reg);
+
+	reg = readl(&regs->status2);
+	writel(reg, &regs->status2);	/* Clear all STATUS2 events via R/W */
+	debug("%s entry: STATUS2 = %08x\n", __func__, reg);
+
+	debug("%s entry: COMMAND = %08x\n", __func__, readl(&regs->command));
+
+	clrsetbits_le32(&regs->command2, SLINK_CMD2_SS_EN_MASK,
+			SLINK_CMD2_TXEN | SLINK_CMD2_RXEN |
+			(slave->cs << SLINK_CMD2_SS_EN_SHIFT));
+	debug("%s entry: COMMAND2 = %08x\n", __func__, readl(&regs->command2));
+
+	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];
+			dout += bytes;
+		}
+
+		num_bytes -= bytes;
+
+		clrsetbits_le32(&regs->command, SLINK_CMD_BIT_LENGTH_MASK,
+				bytes * 8 - 1);
+		writel(tmpdout, &regs->tx_fifo);
+		setbits_le32(&regs->command, SLINK_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 & SLINK_STAT_TXF_EMPTY))
+				break;
+
+			if ((status & (SLINK_STAT_BSY | SLINK_STAT_RDY)) !=
+					SLINK_STAT_RDY)
+				tm++;
+
+			else if (!(status & SLINK_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("%s: transfer ended. Value=%08x, status = %08x\n",
+	      __func__, tmpdin, readl(&regs->status));
+
+	if (ret) {
+		printf("%s: timeout during SPI transfer, tm %d\n",
+		       __func__, ret);
+		return -1;
+	}
+
+	return 0;
+}