[PATCH v6] spi: Add PPC4xx SPI driver
Stefan Roese
sr at denx.de
Thu Jan 8 21:40:50 EST 2009
This adds a SPI driver for the SPI controller found in the IBM/AMCC
4xx PowerPC's.
Signed-off-by: Stefan Roese <sr at denx.de>
Signed-off-by: Wolfgang Ocker <weo at reccoware.de>
Acked-by: Josh Boyer <jwboyer at linux.vnet.ibm.com>
---
Changes in v6:
- Moved comment about high interrupt load to top of file and extended it
by explaining that the 4xx SPI controller has no FIFOs.
- Added parameter checking to setup() routine.
- Removed comment about LSB
- Used of_gpio_count() instead creating own static implementation as
suggested by Anton.
Changes in v5:
- Don't call setupxfer() from setup() so that the baudrate etc
won't get changed while another transfer is active, as suggested
by David Brownell.
- module_{init,exit} moved directly to the functions to which they
apply.
- Use __func__ instead of __FUNCTION__.
Changes in v4:
- Added fixes suggested by Josh Boyer
- Changed compatible property from "ibm,spi" to "ibm,ppc4xx-spi"
Changes in v3:
- When the device is removed the GPIOs are released. The memory
for the GPIO array is freed.
Changes in v2:
- Now the gpios property is correctly decoded and the
resulting gpio numbers are used as the devices chip
selects.
drivers/spi/Kconfig | 7 +
drivers/spi/Makefile | 1 +
drivers/spi/spi_ppc4xx.c | 594 ++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 602 insertions(+), 0 deletions(-)
create mode 100644 drivers/spi/spi_ppc4xx.c
diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index b9d0efb..69d5fee 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -155,6 +155,13 @@ config SPI_ORION
help
This enables using the SPI master controller on the Orion chips.
+config SPI_PPC4xx
+ tristate "PPC4xx SPI Controller"
+ depends on 4xx && SPI_MASTER
+ select SPI_BITBANG
+ help
+ This selects a driver for the PPC4xx SPI Controller.
+
config SPI_PXA2XX
tristate "PXA2xx SSP SPI master"
depends on ARCH_PXA && EXPERIMENTAL
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index ccf18de..a2e5816 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -24,6 +24,7 @@ obj-$(CONFIG_SPI_OMAP24XX) += omap2_mcspi.o
obj-$(CONFIG_SPI_ORION) += orion_spi.o
obj-$(CONFIG_SPI_MPC52xx_PSC) += mpc52xx_psc_spi.o
obj-$(CONFIG_SPI_MPC83xx) += spi_mpc83xx.o
+obj-$(CONFIG_SPI_PPC4xx) += spi_ppc4xx.o
obj-$(CONFIG_SPI_S3C24XX_GPIO) += spi_s3c24xx_gpio.o
obj-$(CONFIG_SPI_S3C24XX) += spi_s3c24xx.o
obj-$(CONFIG_SPI_TXX9) += spi_txx9.o
diff --git a/drivers/spi/spi_ppc4xx.c b/drivers/spi/spi_ppc4xx.c
new file mode 100644
index 0000000..15d433a
--- /dev/null
+++ b/drivers/spi/spi_ppc4xx.c
@@ -0,0 +1,594 @@
+/*
+ * SPI_PPC4XX SPI controller driver.
+ *
+ * Copyright (C) 2007 Gary Jennejohn <garyj at denx.de>
+ * Copyright 2008 Stefan Roese <sr at denx.de>, DENX Software Engineering
+ *
+ * Based in part on drivers/spi/spi_s3c24xx.c
+ *
+ * Copyright (c) 2006 Ben Dooks
+ * Copyright (c) 2006 Simtec Electronics
+ * Ben Dooks <ben at simtec.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ */
+
+/*
+ * The PPC4xx SPI controller has no FIFO so each sent/received byte will
+ * generate an interrupt to the CPU. This can cause high CPU utilization.
+ * This driver allows platforms to reduce the interrupt load on the CPU
+ * during SPI transfers by setting max_speed_hz via the device tree.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/sched.h>
+#include <linux/errno.h>
+#include <linux/wait.h>
+#include <linux/of_platform.h>
+#include <linux/of_spi.h>
+#include <linux/of_gpio.h>
+#include <linux/interrupt.h>
+#include <linux/delay.h>
+
+#include <linux/gpio.h>
+#include <linux/spi/spi.h>
+#include <linux/spi/spi_bitbang.h>
+
+#include <asm/io.h>
+#include <asm/dcr.h>
+#include <asm/dcr-regs.h>
+
+/* bits in mode register - bit 0 ist MSb */
+/* data latched on leading edge of clock, else trailing edge */
+#define SPI_PPC4XX_MODE_SCP (0x80 >> 3)
+/* port enabled */
+#define SPI_PPC4XX_MODE_SPE (0x80 >> 4)
+/* MSB first, else LSB first */
+#define SPI_PPC4XX_MODE_RD (0x80 >> 5)
+/* clock invert - idle clock = 1, active clock = 0; else reversed */
+#define SPI_PPC4XX_MODE_CI (0x80 >> 6)
+/* loopback enable */
+#define SPI_PPC4XX_MODE_IL (0x80 >> 7)
+/* bits in control register */
+/* starts a transfer when set */
+#define SPI_PPC4XX_CR_STR (0x80 >> 7)
+/* bits in status register */
+/* port is busy with a transfer */
+#define SPI_PPC4XX_SR_BSY (0x80 >> 6)
+/* RxD ready */
+#define SPI_PPC4XX_SR_RBR (0x80 >> 7)
+
+/* the spi->mode bits understood by this driver: */
+#define MODEBITS (SPI_CPHA | SPI_CPOL | SPI_CS_HIGH | SPI_LSB_FIRST)
+
+/* clock settings (SCP and CI) for various SPI modes */
+#define SPI_CLK_MODE0 SPI_PPC4XX_MODE_SCP
+#define SPI_CLK_MODE1 0
+#define SPI_CLK_MODE2 SPI_PPC4XX_MODE_CI
+#define SPI_CLK_MODE3 (SPI_PPC4XX_MODE_SCP | SPI_PPC4XX_MODE_CI)
+
+#define DRIVER_NAME "spi_ppc4xx_of"
+
+struct spi_ppc4xx_regs {
+ u8 mode;
+ u8 rxd;
+ u8 txd;
+ u8 cr;
+ u8 sr;
+ u8 dummy;
+ /*
+ * Clock divisor modulus register
+ * This uses the follwing formula:
+ * SCPClkOut = OPBCLK/(4(CDM + 1))
+ * or
+ * CDM = (OPBCLK/4*SCPClkOut) - 1
+ * bit 0 is the MSb!
+ */
+ u8 cdm;
+};
+
+/* SPI Controller driver's private data. */
+struct ppc4xx_spi {
+ /* bitbang has to be first */
+ struct spi_bitbang bitbang;
+ struct completion done;
+
+ u64 mapbase;
+ u64 mapsize;
+ int irqnum;
+ /* need this to set the SPI clock */
+ unsigned int opb_freq;
+
+ /* for transfers */
+ int len;
+ int count;
+ /* data buffers */
+ const unsigned char *tx;
+ unsigned char *rx;
+
+ int *gpios;
+ unsigned int num_gpios;
+
+ struct spi_ppc4xx_regs __iomem *regs; /* pointer to the registers */
+ struct spi_master *master;
+ struct device *dev;
+};
+
+/* need this so we can set the clock in the chipselect routine */
+struct spi_ppc4xx_cs {
+ u8 mode;
+};
+
+static int spi_ppc4xx_txrx(struct spi_device *spi, struct spi_transfer *t)
+{
+ struct ppc4xx_spi *hw;
+ u8 data;
+
+ dev_dbg(&spi->dev, "txrx: tx %p, rx %p, len %d\n",
+ t->tx_buf, t->rx_buf, t->len);
+
+ hw = spi_master_get_devdata(spi->master);
+
+ hw->tx = t->tx_buf;
+ hw->rx = t->rx_buf;
+ hw->len = t->len;
+ hw->count = 0;
+
+ /* send the first byte */
+ data = hw->tx ? hw->tx[0] : 0;
+ out_8(&hw->regs->txd, data);
+ out_8(&hw->regs->cr, SPI_PPC4XX_CR_STR);
+ wait_for_completion(&hw->done);
+
+ return hw->count;
+}
+
+static int spi_ppc4xx_setupxfer(struct spi_device *spi, struct spi_transfer *t)
+{
+ struct ppc4xx_spi *hw = spi_master_get_devdata(spi->master);
+ struct spi_ppc4xx_cs *cs = spi->controller_state;
+ int scr;
+ u8 cdm = 0;
+ u32 speed;
+ u8 bits_per_word;
+
+ bits_per_word = (t) ? t->bits_per_word : spi->bits_per_word;
+ speed = (t) ? t->speed_hz : spi->max_speed_hz;
+
+ if (bits_per_word != 8) {
+ dev_err(&spi->dev, "invalid bits-per-word (%d)\n", bits_per_word);
+ return -EINVAL;
+ }
+
+ if (!speed || (speed > spi->max_speed_hz)) {
+ dev_err(&spi->dev, "invalid speed_hz (%d)\n", speed);
+ return -EINVAL;
+ }
+
+ /* Write new configration */
+ out_8(&hw->regs->mode, cs->mode);
+
+ /* Set the clock */
+ /* opb_freq was already divided by 4 */
+ scr = (hw->opb_freq / speed) - 1;
+ if (scr > 0)
+ cdm = min(scr, 0xff);
+
+ dev_dbg(&spi->dev, "setting pre-scaler to %d (hz %d)\n", cdm, speed);
+
+ if (in_8(&hw->regs->cdm) != cdm)
+ out_8(&hw->regs->cdm, cdm);
+
+ spin_lock(&hw->bitbang.lock);
+ if (!hw->bitbang.busy) {
+ hw->bitbang.chipselect(spi, BITBANG_CS_INACTIVE);
+ /* Need to ndelay here? */
+ }
+ spin_unlock(&hw->bitbang.lock);
+
+ return 0;
+}
+
+static int spi_ppc4xx_setup(struct spi_device *spi)
+{
+ int ret;
+ struct spi_ppc4xx_cs *cs = spi->controller_state;
+ int init = 0;
+
+ if (!spi->bits_per_word)
+ spi->bits_per_word = 8;
+
+ if (spi->bits_per_word != 8) {
+ dev_err(&spi->dev, "invalid bits-per-word (%d)\n",
+ spi->bits_per_word);
+ return -EINVAL;
+ }
+
+ if (!spi->max_speed_hz) {
+ dev_err(&spi->dev, "invalid max_speed_hz (must be non-zero)\n");
+ return -EINVAL;
+ }
+
+ if (spi->mode & ~MODEBITS) {
+ dev_dbg(&spi->dev, "setup: unsupported mode bits %x\n",
+ spi->mode & ~MODEBITS);
+ return -EINVAL;
+ }
+
+ if (cs == NULL) {
+ cs = kzalloc(sizeof *cs, GFP_KERNEL);
+ if (!cs)
+ return -ENOMEM;
+ spi->controller_state = cs;
+
+ /*
+ * First time called, so let's init the SPI controller
+ * at the end of this function
+ */
+ init = 1;
+ }
+
+ /*
+ * We set all bits of the SPI0_MODE register, so,
+ * no need to read-modify-write
+ */
+ cs->mode = SPI_PPC4XX_MODE_SPE;
+
+ switch (spi->mode & (SPI_CPHA | SPI_CPOL)) {
+ case SPI_MODE_0:
+ cs->mode |= SPI_CLK_MODE0;
+ break;
+ case SPI_MODE_1:
+ cs->mode |= SPI_CLK_MODE1;
+ break;
+ case SPI_MODE_2:
+ cs->mode |= SPI_CLK_MODE2;
+ break;
+ case SPI_MODE_3:
+ cs->mode |= SPI_CLK_MODE3;
+ break;
+ }
+
+ if (spi->mode & SPI_LSB_FIRST)
+ cs->mode |= SPI_PPC4XX_MODE_RD;
+
+ /*
+ * New configuration (mode, speed etc) will be written to the
+ * controller in spi_ppc4xx_setupxfer(). Only call
+ * spi_ppc4xx_setupxfer() directly upon first initialization.
+ */
+ if (init) {
+ ret = spi_ppc4xx_setupxfer(spi, NULL);
+ if (ret < 0) {
+ dev_err(&spi->dev, "setupxfer returned %d\n", ret);
+ return ret;
+ }
+ }
+
+ dev_dbg(&spi->dev, "%s: mode %d, %u bpw, %d hz\n",
+ __func__, spi->mode, spi->bits_per_word,
+ spi->max_speed_hz);
+
+ return 0;
+}
+
+static void spi_ppc4xx_chipsel(struct spi_device *spi, int value)
+{
+ struct ppc4xx_spi *hw = spi_master_get_devdata(spi->master);
+ unsigned int cspol = spi->mode & SPI_CS_HIGH ? 1 : 0;
+ unsigned int cs = spi->chip_select;
+
+ if (!hw->num_gpios)
+ return;
+
+ if (cs >= hw->num_gpios)
+ return;
+
+ if (value != BITBANG_CS_INACTIVE && value != BITBANG_CS_ACTIVE)
+ return;
+
+ if (value == BITBANG_CS_INACTIVE)
+ cspol = !cspol;
+
+ gpio_set_value(hw->gpios[cs], cspol);
+}
+
+static irqreturn_t spi_ppc4xx_int(int irq, void *dev_id)
+{
+ struct ppc4xx_spi *hw;
+ u8 status;
+ u8 data;
+ unsigned int count;
+
+ hw = (struct ppc4xx_spi *)dev_id;
+
+ status = in_8(&hw->regs->sr);
+ if (!status)
+ return IRQ_NONE;
+
+ /* should never happen but check anyway */
+ if (status & SPI_PPC4XX_SR_BSY) {
+ u8 lstatus;
+ int cnt = 0;
+
+ dev_dbg(hw->dev, "got interrupt but spi still busy?\n");
+ do {
+ ndelay(10);
+ lstatus = in_8(&hw->regs->sr);
+ } while (++cnt < 100 && lstatus & SPI_PPC4XX_SR_BSY);
+
+ if (cnt >= 100) {
+ dev_err(hw->dev, "busywait: too many loops!\n");
+ complete(&hw->done);
+ return IRQ_HANDLED;
+ } else {
+ /* status is always 1 (RBR) here */
+ status = in_8(&hw->regs->sr);
+ dev_dbg(hw->dev, "loops %d status %x\n", cnt, status);
+ }
+ }
+
+ count = hw->count;
+ hw->count++;
+
+ if (status & SPI_PPC4XX_SR_RBR) {
+ /* Data Ready */
+ data = in_8(&hw->regs->rxd);
+ if (hw->rx)
+ hw->rx[count] = data;
+ }
+
+ count++;
+
+ if (count < hw->len) {
+ data = hw->tx ? hw->tx[count] : 0;
+ out_8(&hw->regs->txd, data);
+ out_8(&hw->regs->cr, SPI_PPC4XX_CR_STR);
+ } else {
+ complete(&hw->done);
+ }
+
+ return IRQ_HANDLED;
+}
+
+static void spi_ppc4xx_cleanup(struct spi_device *spi)
+{
+ kfree(spi->controller_state);
+}
+
+static void spi_ppc4xx_enable(struct ppc4xx_spi *hw)
+{
+ /*
+ * On all 4xx PPC's the SPI bus is shared/multiplexed with
+ * the 2nd I2C bus. We need to enable the the SPI bus before
+ * using it.
+ */
+
+ /* need to clear bit 14 to enable SPC */
+ dcri_clrset(SDR0, SDR0_PFC1, 0x80000000 >> 14, 0);
+}
+
+static void free_gpios(struct ppc4xx_spi *hw)
+{
+ if (hw->num_gpios) {
+ int i;
+ for (i = 0; i < hw->num_gpios; i++)
+ gpio_free(hw->gpios[i]);
+
+ kfree(hw->gpios);
+ hw->gpios = NULL;
+ }
+}
+
+/*
+ * of_device layer stuff...
+ */
+static int __init spi_ppc4xx_of_probe(struct of_device *op,
+ const struct of_device_id *match)
+{
+ struct ppc4xx_spi *hw;
+ struct spi_master *master;
+ struct spi_bitbang *bbp;
+ struct resource resource;
+ struct device_node *np = op->node;
+ struct device *dev = &op->dev;
+ struct device_node *opbnp;
+ int ret;
+ const unsigned int *clk;
+
+ master = spi_alloc_master(dev, sizeof *hw);
+ if (master == NULL)
+ return -ENOMEM;
+ dev_set_drvdata(dev, master);
+ hw = spi_master_get_devdata(master);
+ memset(hw, 0, sizeof(struct ppc4xx_spi));
+
+ hw->master = spi_master_get(master);
+ hw->dev = dev;
+
+ init_completion(&hw->done);
+
+ hw->num_gpios = of_gpio_count(np);
+ if (hw->num_gpios) {
+ int i;
+
+ hw->gpios = kzalloc(sizeof(int) * hw->num_gpios,
+ GFP_KERNEL);
+ if (!hw->gpios) {
+ ret = -ENOMEM;
+ goto free_master;
+ }
+
+ for (i = 0; i < hw->num_gpios; i++) {
+ int gpio = of_get_gpio(np, i);
+ if (gpio < 0) {
+ dev_err(dev, "Invalid gpio spec %d\n", i);
+ ret = gpio;
+ goto free_gpios;
+ }
+
+ ret = gpio_request(gpio, np->name);
+ if (ret < 0) {
+ dev_err(dev, "gpio %d already in use\n", i);
+ ret = gpio;
+ goto free_gpios;
+ }
+
+ gpio_direction_output(gpio, 0);
+ hw->gpios[i] = gpio;
+ }
+ }
+
+ /* Setup the state for the bitbang driver */
+ bbp = &hw->bitbang;
+ bbp->master = hw->master;
+ bbp->setup_transfer = spi_ppc4xx_setupxfer;
+ bbp->chipselect = spi_ppc4xx_chipsel;
+ bbp->txrx_bufs = spi_ppc4xx_txrx;
+ bbp->use_dma = 0;
+ bbp->master->setup = spi_ppc4xx_setup;
+ bbp->master->cleanup = spi_ppc4xx_cleanup;
+ /* only one SPI controller */
+ bbp->master->bus_num = 0;
+ if (bbp->master->num_chipselect == 0) {
+ /* this many pins in al GPIO controllers */
+ bbp->master->num_chipselect = hw->num_gpios;
+ }
+
+ /* Get the clock for the OPB */
+ opbnp = of_find_compatible_node(NULL, NULL, "ibm,opb");
+ if (opbnp == NULL) {
+ dev_err(dev, "OPB: cannot find node\n");
+ ret = -ENODEV;
+ goto free_gpios;
+ }
+ /* Get the clock (Hz) for the OPB */
+ clk = of_get_property(opbnp, "clock-frequency", NULL);
+ if (clk == NULL) {
+ dev_err(dev, "OPB: no clock-frequency property set\n");
+ of_node_put(opbnp);
+ ret = -ENODEV;
+ goto free_gpios;
+ }
+ hw->opb_freq = *clk;
+ hw->opb_freq >>= 2;
+ of_node_put(opbnp);
+
+ ret = of_address_to_resource(np, 0, &resource);
+ if (ret) {
+ dev_err(dev, "error while parsing device node resource\n");
+ goto free_gpios;
+ }
+ hw->mapbase = resource.start;
+ hw->mapsize = resource.end - resource.start + 1;
+
+ /* Sanity check */
+ if (hw->mapsize < sizeof(struct spi_ppc4xx_regs)) {
+ dev_err(dev, "too small to map registers\n");
+ ret = -EINVAL;
+ goto free_gpios;
+ }
+
+ /* Request IRQ */
+ hw->irqnum = irq_of_parse_and_map(np, 0);
+ ret = request_irq(hw->irqnum, spi_ppc4xx_int,
+ IRQF_DISABLED, "spi_ppc4xx_of", (void *)hw);
+ if (ret) {
+ dev_err(dev, "unable to allocate interrupt\n");
+ goto free_gpios;
+ }
+
+ if (!request_mem_region(hw->mapbase, hw->mapsize, DRIVER_NAME)) {
+ dev_err(dev, "resource unavailable\n");
+ ret = -EBUSY;
+ goto request_mem_error;
+ }
+
+ hw->regs = ioremap(hw->mapbase, sizeof(struct spi_ppc4xx_regs));
+
+ if (!hw->regs) {
+ dev_err(dev, "unable to memory map registers\n");
+ ret = -ENXIO;
+ goto map_io_error;
+ }
+
+ spi_ppc4xx_enable(hw);
+
+ /* Finally register our spi controller */
+ dev->dma_mask = 0;
+ ret = spi_bitbang_start(bbp);
+ if (ret) {
+ dev_err(dev, "failed to register SPI master\n");
+ goto unmap_regs;
+ }
+
+ dev_info(dev, "driver initialized\n");
+ of_register_spi_devices(master, np);
+
+ return 0;
+
+unmap_regs:
+ iounmap(hw->regs);
+map_io_error:
+ release_mem_region(hw->mapbase, hw->mapsize);
+request_mem_error:
+ free_irq(hw->irqnum, hw);
+free_gpios:
+ free_gpios(hw);
+free_master:
+ dev_set_drvdata(dev, NULL);
+ spi_master_put(master);
+
+ dev_err(dev, "initialization failed\n");
+ return ret;
+}
+
+static int __exit spi_ppc4xx_of_remove(struct of_device *op)
+{
+ struct spi_master *master = dev_get_drvdata(&op->dev);
+ struct ppc4xx_spi *hw = spi_master_get_devdata(master);
+
+ spi_bitbang_stop(&hw->bitbang);
+ dev_set_drvdata(&op->dev, NULL);
+ release_mem_region(hw->mapbase, hw->mapsize);
+ free_irq(hw->irqnum, hw);
+ iounmap(hw->regs);
+ free_gpios(hw);
+ return 0;
+}
+
+static struct of_device_id spi_ppc4xx_of_match[] = {
+ { .compatible = "ibm,ppc4xx-spi", },
+ {},
+};
+
+MODULE_DEVICE_TABLE(of, spi_ppc4xx_of_match);
+
+static struct of_platform_driver spi_ppc4xx_of_driver = {
+ .match_table = spi_ppc4xx_of_match,
+ .probe = spi_ppc4xx_of_probe,
+ .remove = __exit_p(spi_ppc4xx_of_remove),
+ .driver = {
+ .name = DRIVER_NAME,
+ .owner = THIS_MODULE,
+ },
+};
+
+static int __init spi_ppc4xx_init(void)
+{
+ return of_register_platform_driver(&spi_ppc4xx_of_driver);
+}
+module_init(spi_ppc4xx_init);
+
+static void __exit spi_ppc4xx_exit(void)
+{
+ of_unregister_platform_driver(&spi_ppc4xx_of_driver);
+}
+module_exit(spi_ppc4xx_exit);
+
+MODULE_AUTHOR("Gary Jennejohn & Stefan Roese");
+MODULE_DESCRIPTION("Simple PPC4xx SPI Driver");
+MODULE_LICENSE("GPL");
--
1.6.1
More information about the Linuxppc-dev
mailing list