nios2: Add Altera SPI master driver

Signed-off-by: Franck Jullien <franck.jullien@gmail.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

1 files changed, 227 insertions, 0 deletions

diff --git a/drivers/spi/altera_spi.c b/drivers/spi/altera_spi.c
new file mode 100644
index 0000000000..2c02d7af63
--- /dev/null
+++ b/drivers/spi/altera_spi.c
@@ -0,0 +1,227 @@
+/*
+ * (C) Copyright 2011 - Franck JULLIEN <elec4fun@gmail.com>
+ *
+ * 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 <init.h>
+#include <driver.h>
+#include <spi/spi.h>
+#include <asm/io.h>
+#include <asm/spi.h>
+#include <asm/nios2-io.h>
+
+static int altera_spi_setup(struct spi_device *spi)
+{
+	struct spi_master *master = spi->master;
+	struct device_d spi_dev = spi->dev;
+	struct altera_spi *altera_spi = container_of(master, struct altera_spi, master);
+
+	if (spi->bits_per_word != altera_spi->databits) {
+		dev_err(master->dev, " master doesn't support %d bits per word requested by %s\n",
+			spi->bits_per_word, spi_dev.name);
+		return -1;
+	}
+
+	if ((spi->mode & (SPI_CPHA | SPI_CPOL)) != altera_spi->mode) {
+		dev_err(master->dev, " master doesn't support SPI_MODE%d requested by %s\n",
+			spi->mode & (SPI_CPHA | SPI_CPOL), spi_dev.name);
+		return -1;
+	}
+
+	if (spi->max_speed_hz < altera_spi->speed) {
+		dev_err(master->dev, " frequency is too high for %s\n", spi_dev.name);
+		return -1;
+	}
+
+	dev_dbg(master->dev, " mode 0x%08x, bits_per_word: %d, speed: %d\n",
+		spi->mode, spi->bits_per_word, altera_spi->speed);
+
+	return 0;
+}
+
+
+static unsigned int altera_spi_xchg_single(struct altera_spi *altera_spi, unsigned int data)
+{
+	struct nios_spi *nios_spi = altera_spi->regs;
+
+	while (!(readl(&nios_spi->status) & NIOS_SPI_TRDY));
+	writel(data, &nios_spi->txdata);
+
+	while (!(readl(&nios_spi->status) & NIOS_SPI_RRDY));
+
+	return readl(&nios_spi->rxdata);
+}
+
+/*
+ * When using SPI_CS_HIGH devices, only one device is allowed to be
+ * connected to the Altera SPI master. This limitation is due to the
+ * emulation of an active high CS by writing 0 to the slaveselect register
+ * (this produce a '1' to all CS pins).
+ */
+
+static void altera_spi_cs_active(struct spi_device *spi)
+{
+	struct altera_spi *altera_spi = container_of(spi->master, struct altera_spi, master);
+	struct nios_spi *nios_spi = altera_spi->regs;
+	uint32_t tmp;
+
+	if (spi->mode & SPI_CS_HIGH) {
+		tmp = readw(&nios_spi->control);
+		writew(tmp & ~NIOS_SPI_SSO, &nios_spi->control);
+		writel(0, &nios_spi->slaveselect);
+	} else {
+		writel(1 << spi->chip_select, &nios_spi->slaveselect);
+		tmp = readl(&nios_spi->control);
+		writel(tmp | NIOS_SPI_SSO, &nios_spi->control);
+	}
+}
+
+static void altera_spi_cs_inactive(struct spi_device *spi)
+{
+	struct altera_spi *altera_spi = container_of(spi->master, struct altera_spi, master);
+	struct nios_spi *nios_spi = altera_spi->regs;
+	uint32_t tmp;
+
+	if (spi->mode & SPI_CS_HIGH) {
+		writel(1 << spi->chip_select, &nios_spi->slaveselect);
+		tmp = readl(&nios_spi->control);
+		writel(tmp | NIOS_SPI_SSO, &nios_spi->control);
+	} else {
+		tmp = readw(&nios_spi->control);
+		writew(tmp & ~NIOS_SPI_SSO, &nios_spi->control);
+	}
+}
+
+static unsigned altera_spi_do_xfer(struct spi_device *spi, struct spi_transfer *t)
+{
+	struct altera_spi *altera_spi = container_of(spi->master, struct altera_spi, master);
+	int word_len = spi->bits_per_word;
+	unsigned retval = 0;
+	u32 txval;
+	u32 rxval;
+
+	word_len = spi->bits_per_word;
+
+	if (word_len <= 8) {
+		const u8 *txbuf = t->tx_buf;
+		u8 *rxbuf = t->rx_buf;
+		int i = 0;
+
+		while (i < t->len) {
+			txval = txbuf ? txbuf[i] : 0;
+			rxval = altera_spi_xchg_single(altera_spi, txval);
+			if (rxbuf)
+				rxbuf[i] = rxval;
+			i++;
+			retval++;
+		}
+	} else if (word_len <= 16) {
+		const u16 *txbuf = t->tx_buf;
+		u16 *rxbuf = t->rx_buf;
+		int i = 0;
+
+		while (i < t->len >> 1) {
+			txval = txbuf ? txbuf[i] : 0;
+			rxval = altera_spi_xchg_single(altera_spi, txval);
+			if (rxbuf)
+				rxbuf[i] = rxval;
+			i++;
+			retval += 2;
+		}
+	} else if (word_len <= 32) {
+		const u32 *txbuf = t->tx_buf;
+		u32 *rxbuf = t->rx_buf;
+		int i = 0;
+
+		while (i < t->len >> 2) {
+			txval = txbuf ? txbuf[i] : 0;
+			rxval = altera_spi_xchg_single(altera_spi, txval);
+			if (rxbuf)
+				rxbuf[i] = rxval;
+			i++;
+			retval += 4;
+		}
+	}
+
+	return retval;
+}
+
+static int altera_spi_transfer(struct spi_device *spi, struct spi_message *mesg)
+{
+	struct altera_spi *altera_spi = container_of(spi->master, struct altera_spi, master);
+	struct nios_spi *nios_spi = altera_spi->regs;
+	struct spi_transfer *t;
+
+	altera_spi_cs_active(spi);
+
+	mesg->actual_length = 0;
+
+	list_for_each_entry(t, &mesg->transfers, transfer_list) {
+		mesg->actual_length += altera_spi_do_xfer(spi, t);
+	}
+
+	/* Wait the end of any pending transfer */
+	while ((readl(&nios_spi->status) & NIOS_SPI_TMT) == 0);
+
+	altera_spi_cs_inactive(spi);
+
+	return 0;
+}
+
+static int altera_spi_probe(struct device_d *dev)
+{
+	struct spi_master *master;
+	struct altera_spi *altera_spi;
+	struct spi_altera_master *pdata = dev->platform_data;
+	struct nios_spi *nios_spi;
+
+	altera_spi = xzalloc(sizeof(*altera_spi));
+
+	master = &altera_spi->master;
+	master->dev = dev;
+
+	master->setup = altera_spi_setup;
+	master->transfer = altera_spi_transfer;
+	master->num_chipselect = pdata->num_chipselect;
+
+	altera_spi->regs = dev_request_mem_region(dev, 0);
+	altera_spi->databits = pdata->databits;
+	altera_spi->speed = pdata->speed;
+	altera_spi->mode = pdata->spi_mode;
+
+	nios_spi = altera_spi->regs;
+	writel(0, &nios_spi->slaveselect);
+	writel(0, &nios_spi->control);
+
+	spi_register_master(master);
+
+	return 0;
+}
+
+static struct driver_d altera_spi_driver = {
+	.name  = "altera_spi",
+	.probe = altera_spi_probe,
+};
+
+static int altera_spi_driver_init(void)
+{
+	return register_driver(&altera_spi_driver);
+}
+
+device_initcall(altera_spi_driver_init);