--- /dev/null
+/*
+ * Driver for Broadcom BCM2835 SPI Controllers
+ *
+ * Copyright (C) 2012 Chris Boot
+ * Copyright (C) 2013 Stephen Warren
+ *
+ * This driver is inspired by:
+ * spi-ath79.c, Copyright (C) 2009-2011 Gabor Juhos <juhosg@openwrt.org>
+ * spi-atmel.c, Copyright (C) 2006 Atmel Corporation
+ *
+ * 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 <linux/clk.h>
+#include <linux/completion.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_irq.h>
+#include <linux/of_device.h>
+#include <linux/spi/spi.h>
+
+/* SPI register offsets */
+#define BCM2835_SPI_CS 0x00
+#define BCM2835_SPI_FIFO 0x04
+#define BCM2835_SPI_CLK 0x08
+#define BCM2835_SPI_DLEN 0x0c
+#define BCM2835_SPI_LTOH 0x10
+#define BCM2835_SPI_DC 0x14
+
+/* Bitfields in CS */
+#define BCM2835_SPI_CS_LEN_LONG 0x02000000
+#define BCM2835_SPI_CS_DMA_LEN 0x01000000
+#define BCM2835_SPI_CS_CSPOL2 0x00800000
+#define BCM2835_SPI_CS_CSPOL1 0x00400000
+#define BCM2835_SPI_CS_CSPOL0 0x00200000
+#define BCM2835_SPI_CS_RXF 0x00100000
+#define BCM2835_SPI_CS_RXR 0x00080000
+#define BCM2835_SPI_CS_TXD 0x00040000
+#define BCM2835_SPI_CS_RXD 0x00020000
+#define BCM2835_SPI_CS_DONE 0x00010000
+#define BCM2835_SPI_CS_LEN 0x00002000
+#define BCM2835_SPI_CS_REN 0x00001000
+#define BCM2835_SPI_CS_ADCS 0x00000800
+#define BCM2835_SPI_CS_INTR 0x00000400
+#define BCM2835_SPI_CS_INTD 0x00000200
+#define BCM2835_SPI_CS_DMAEN 0x00000100
+#define BCM2835_SPI_CS_TA 0x00000080
+#define BCM2835_SPI_CS_CSPOL 0x00000040
+#define BCM2835_SPI_CS_CLEAR_RX 0x00000020
+#define BCM2835_SPI_CS_CLEAR_TX 0x00000010
+#define BCM2835_SPI_CS_CPOL 0x00000008
+#define BCM2835_SPI_CS_CPHA 0x00000004
+#define BCM2835_SPI_CS_CS_10 0x00000002
+#define BCM2835_SPI_CS_CS_01 0x00000001
+
+#define BCM2835_SPI_TIMEOUT_MS 30000
+#define BCM2835_SPI_MODE_BITS (SPI_CPOL | SPI_CPHA | SPI_CS_HIGH | SPI_NO_CS)
+
+#define DRV_NAME "spi-bcm2835"
+
+struct bcm2835_spi {
+ void __iomem *regs;
+ struct clk *clk;
+ int irq;
+ struct completion done;
+ const u8 *tx_buf;
+ u8 *rx_buf;
+ int len;
+};
+
+static inline u32 bcm2835_rd(struct bcm2835_spi *bs, unsigned reg)
+{
+ return readl(bs->regs + reg);
+}
+
+static inline void bcm2835_wr(struct bcm2835_spi *bs, unsigned reg, u32 val)
+{
+ writel(val, bs->regs + reg);
+}
+
+static inline void bcm2835_rd_fifo(struct bcm2835_spi *bs, int len)
+{
+ u8 byte;
+
+ while (len--) {
+ byte = bcm2835_rd(bs, BCM2835_SPI_FIFO);
+ if (bs->rx_buf)
+ *bs->rx_buf++ = byte;
+ }
+}
+
+static inline void bcm2835_wr_fifo(struct bcm2835_spi *bs, int len)
+{
+ u8 byte;
+
+ if (len > bs->len)
+ len = bs->len;
+
+ while (len--) {
+ byte = bs->tx_buf ? *bs->tx_buf++ : 0;
+ bcm2835_wr(bs, BCM2835_SPI_FIFO, byte);
+ bs->len--;
+ }
+}
+
+static irqreturn_t bcm2835_spi_interrupt(int irq, void *dev_id)
+{
+ struct spi_master *master = dev_id;
+ struct bcm2835_spi *bs = spi_master_get_devdata(master);
+ u32 cs = bcm2835_rd(bs, BCM2835_SPI_CS);
+
+ /*
+ * RXR - RX needs Reading. This means 12 (or more) bytes have been
+ * transmitted and hence 12 (or more) bytes have been received.
+ *
+ * The FIFO is 16-bytes deep. We check for this interrupt to keep the
+ * FIFO full; we have a 4-byte-time buffer for IRQ latency. We check
+ * this before DONE (TX empty) just in case we delayed processing this
+ * interrupt for some reason.
+ *
+ * We only check for this case if we have more bytes to TX; at the end
+ * of the transfer, we ignore this pipelining optimization, and let
+ * bcm2835_spi_finish_transfer() drain the RX FIFO.
+ */
+ if (bs->len && (cs & BCM2835_SPI_CS_RXR)) {
+ /* Read 12 bytes of data */
+ bcm2835_rd_fifo(bs, 12);
+
+ /* Write up to 12 bytes */
+ bcm2835_wr_fifo(bs, 12);
+
+ /*
+ * We must have written something to the TX FIFO due to the
+ * bs->len check above, so cannot be DONE. Hence, return
+ * early. Note that DONE could also be set if we serviced an
+ * RXR interrupt really late.
+ */
+ return IRQ_HANDLED;
+ }
+
+ /*
+ * DONE - TX empty. This occurs when we first enable the transfer
+ * since we do not pre-fill the TX FIFO. At any other time, given that
+ * we refill the TX FIFO above based on RXR, and hence ignore DONE if
+ * RXR is set, DONE really does mean end-of-transfer.
+ */
+ if (cs & BCM2835_SPI_CS_DONE) {
+ if (bs->len) { /* First interrupt in a transfer */
+ bcm2835_wr_fifo(bs, 16);
+ } else { /* Transfer complete */
+ /* Disable SPI interrupts */
+ cs &= ~(BCM2835_SPI_CS_INTR | BCM2835_SPI_CS_INTD);
+ bcm2835_wr(bs, BCM2835_SPI_CS, cs);
+
+ /*
+ * Wake up bcm2835_spi_transfer_one(), which will call
+ * bcm2835_spi_finish_transfer(), to drain the RX FIFO.
+ */
+ complete(&bs->done);
+ }
+
+ return IRQ_HANDLED;
+ }
+
+ return IRQ_NONE;
+}
+
+static int bcm2835_spi_check_transfer(struct spi_device *spi,
+ struct spi_transfer *tfr)
+{
+ /* tfr==NULL when called from bcm2835_spi_setup() */
+ u32 bpw = tfr ? tfr->bits_per_word : spi->bits_per_word;
+
+ switch (bpw) {
+ case 8:
+ break;
+ default:
+ dev_err(&spi->dev, "unsupported bits_per_word=%d\n", bpw);
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+static int bcm2835_spi_start_transfer(struct spi_device *spi,
+ struct spi_transfer *tfr)
+{
+ struct bcm2835_spi *bs = spi_master_get_devdata(spi->master);
+ unsigned long spi_hz, clk_hz, cdiv;
+ u32 cs = BCM2835_SPI_CS_INTR | BCM2835_SPI_CS_INTD | BCM2835_SPI_CS_TA;
+
+ spi_hz = tfr->speed_hz;
+ clk_hz = clk_get_rate(bs->clk);
+
+ if (spi_hz >= clk_hz / 2) {
+ cdiv = 2; /* clk_hz/2 is the fastest we can go */
+ } else if (spi_hz) {
+ /* CDIV must be a power of two */
+ cdiv = roundup_pow_of_two(DIV_ROUND_UP(clk_hz, spi_hz));
+
+ if (cdiv >= 65536)
+ cdiv = 0; /* 0 is the slowest we can go */
+ } else
+ cdiv = 0; /* 0 is the slowest we can go */
+
+ if (spi->mode & SPI_CPOL)
+ cs |= BCM2835_SPI_CS_CPOL;
+ if (spi->mode & SPI_CPHA)
+ cs |= BCM2835_SPI_CS_CPHA;
+
+ if (!(spi->mode & SPI_NO_CS)) {
+ if (spi->mode & SPI_CS_HIGH) {
+ cs |= BCM2835_SPI_CS_CSPOL;
+ cs |= BCM2835_SPI_CS_CSPOL0 << spi->chip_select;
+ }
+
+ cs |= spi->chip_select;
+ }
+
+ INIT_COMPLETION(bs->done);
+ bs->tx_buf = tfr->tx_buf;
+ bs->rx_buf = tfr->rx_buf;
+ bs->len = tfr->len;
+
+ bcm2835_wr(bs, BCM2835_SPI_CLK, cdiv);
+ /*
+ * Enable the HW block. This will immediately trigger a DONE (TX
+ * empty) interrupt, upon which we will fill the TX FIFO with the
+ * first TX bytes. Pre-filling the TX FIFO here to avoid the
+ * interrupt doesn't work:-(
+ */
+ bcm2835_wr(bs, BCM2835_SPI_CS, cs);
+
+ return 0;
+}
+
+static int bcm2835_spi_finish_transfer(struct spi_device *spi,
+ struct spi_transfer *tfr, bool cs_change)
+{
+ struct bcm2835_spi *bs = spi_master_get_devdata(spi->master);
+ u32 cs = bcm2835_rd(bs, BCM2835_SPI_CS);
+
+ /* Drain RX FIFO */
+ while (cs & BCM2835_SPI_CS_RXD) {
+ bcm2835_rd_fifo(bs, 1);
+ cs = bcm2835_rd(bs, BCM2835_SPI_CS);
+ }
+
+ if (tfr->delay_usecs)
+ udelay(tfr->delay_usecs);
+
+ if (cs_change)
+ /* Clear TA flag */
+ bcm2835_wr(bs, BCM2835_SPI_CS, cs & ~BCM2835_SPI_CS_TA);
+
+ return 0;
+}
+
+static int bcm2835_spi_setup(struct spi_device *spi)
+{
+ int ret;
+
+ ret = bcm2835_spi_check_transfer(spi, NULL);
+ if (ret) {
+ dev_err(&spi->dev, "setup: invalid message\n");
+ return ret;
+ }
+
+ return 0;
+}
+
+static int bcm2835_spi_transfer_one(struct spi_master *master,
+ struct spi_message *mesg)
+{
+ struct bcm2835_spi *bs = spi_master_get_devdata(master);
+ struct spi_transfer *tfr;
+ struct spi_device *spi = mesg->spi;
+ int err = 0;
+ unsigned int timeout;
+ bool cs_change;
+
+ list_for_each_entry(tfr, &mesg->transfers, transfer_list) {
+ err = bcm2835_spi_check_transfer(spi, tfr);
+ if (err)
+ goto out;
+
+ err = bcm2835_spi_start_transfer(spi, tfr);
+ if (err)
+ goto out;
+
+ timeout = wait_for_completion_timeout(&bs->done,
+ msecs_to_jiffies(BCM2835_SPI_TIMEOUT_MS));
+ if (!timeout) {
+ err = -ETIMEDOUT;
+ goto out;
+ }
+
+ cs_change = tfr->cs_change ||
+ list_is_last(&tfr->transfer_list, &mesg->transfers);
+
+ err = bcm2835_spi_finish_transfer(spi, tfr, cs_change);
+ if (err)
+ goto out;
+
+ mesg->actual_length += (tfr->len - bs->len);
+ }
+
+out:
+ /* Clear FIFOs, and disable the HW block */
+ bcm2835_wr(bs, BCM2835_SPI_CS,
+ BCM2835_SPI_CS_CLEAR_RX | BCM2835_SPI_CS_CLEAR_TX);
+ mesg->status = err;
+ spi_finalize_current_message(master);
+
+ return 0;
+}
+
+static int bcm2835_spi_probe(struct platform_device *pdev)
+{
+ struct spi_master *master;
+ struct bcm2835_spi *bs;
+ struct resource *res;
+ int err;
+
+ master = spi_alloc_master(&pdev->dev, sizeof(*bs));
+ if (!master) {
+ dev_err(&pdev->dev, "spi_alloc_master() failed\n");
+ return -ENOMEM;
+ }
+
+ platform_set_drvdata(pdev, master);
+
+ master->mode_bits = BCM2835_SPI_MODE_BITS;
+ master->bus_num = -1;
+ master->num_chipselect = 3;
+ master->setup = bcm2835_spi_setup;
+ master->transfer_one_message = bcm2835_spi_transfer_one;
+ master->dev.of_node = pdev->dev.of_node;
+
+ bs = spi_master_get_devdata(master);
+
+ init_completion(&bs->done);
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ if (!res) {
+ dev_err(&pdev->dev, "could not get memory resource\n");
+ err = -ENODEV;
+ goto out_master_put;
+ }
+
+ bs->regs = devm_request_and_ioremap(&pdev->dev, res);
+ if (!bs->regs) {
+ dev_err(&pdev->dev, "could not request/map memory region\n");
+ err = -ENODEV;
+ goto out_master_put;
+ }
+
+ bs->clk = devm_clk_get(&pdev->dev, NULL);
+ if (IS_ERR(bs->clk)) {
+ err = PTR_ERR(bs->clk);
+ dev_err(&pdev->dev, "could not get clk: %d\n", err);
+ goto out_master_put;
+ }
+
+ bs->irq = irq_of_parse_and_map(pdev->dev.of_node, 0);
+ if (bs->irq <= 0) {
+ dev_err(&pdev->dev, "could not get IRQ: %d\n", bs->irq);
+ err = bs->irq ? bs->irq : -ENODEV;
+ goto out_master_put;
+ }
+
+ clk_prepare_enable(bs->clk);
+
+ err = request_irq(bs->irq, bcm2835_spi_interrupt, 0,
+ dev_name(&pdev->dev), master);
+ if (err) {
+ dev_err(&pdev->dev, "could not request IRQ: %d\n", err);
+ goto out_clk_disable;
+ }
+
+ /* initialise the hardware */
+ bcm2835_wr(bs, BCM2835_SPI_CS,
+ BCM2835_SPI_CS_CLEAR_RX | BCM2835_SPI_CS_CLEAR_TX);
+
+ err = spi_register_master(master);
+ if (err) {
+ dev_err(&pdev->dev, "could not register SPI master: %d\n", err);
+ goto out_free_irq;
+ }
+
+ return 0;
+
+out_free_irq:
+ free_irq(bs->irq, master);
+out_clk_disable:
+ clk_disable_unprepare(bs->clk);
+out_master_put:
+ spi_master_put(master);
+ return err;
+}
+
+static int bcm2835_spi_remove(struct platform_device *pdev)
+{
+ struct spi_master *master = platform_get_drvdata(pdev);
+ struct bcm2835_spi *bs = spi_master_get_devdata(master);
+
+ free_irq(bs->irq, master);
+ spi_unregister_master(master);
+
+ /* Clear FIFOs, and disable the HW block */
+ bcm2835_wr(bs, BCM2835_SPI_CS,
+ BCM2835_SPI_CS_CLEAR_RX | BCM2835_SPI_CS_CLEAR_TX);
+
+ clk_disable_unprepare(bs->clk);
+ spi_master_put(master);
+
+ return 0;
+}
+
+static const struct of_device_id bcm2835_spi_match[] = {
+ { .compatible = "brcm,bcm2835-spi", },
+ {}
+};
+MODULE_DEVICE_TABLE(of, bcm2835_spi_match);
+
+static struct platform_driver bcm2835_spi_driver = {
+ .driver = {
+ .name = DRV_NAME,
+ .owner = THIS_MODULE,
+ .of_match_table = bcm2835_spi_match,
+ },
+ .probe = bcm2835_spi_probe,
+ .remove = bcm2835_spi_remove,
+};
+module_platform_driver(bcm2835_spi_driver);
+
+MODULE_DESCRIPTION("SPI controller driver for Broadcom BCM2835");
+MODULE_AUTHOR("Chris Boot <bootc@bootc.net>");
+MODULE_LICENSE("GPL v2");
projects / linux-beck.git / commitdiff