diff options
Diffstat (limited to 'drivers/spi/ath79_spi.c')
| -rw-r--r-- | drivers/spi/ath79_spi.c | 292 |
1 files changed, 292 insertions, 0 deletions
diff --git a/drivers/spi/ath79_spi.c b/drivers/spi/ath79_spi.c new file mode 100644 index 00000000000..fcff810ea3b --- /dev/null +++ b/drivers/spi/ath79_spi.c @@ -0,0 +1,292 @@ +/* + * SPI controller driver for the Atheros AR71XX/AR724X/AR913X SoCs + * + * Copyright (C) 2009-2011 Gabor Juhos <juhosg@openwrt.org> + * + * This driver has been based on the spi-gpio.c: + * Copyright (C) 2006,2008 David Brownell + * + * 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. + * + */ + +#include <linux/kernel.h> +#include <linux/init.h> +#include <linux/delay.h> +#include <linux/spinlock.h> +#include <linux/workqueue.h> +#include <linux/platform_device.h> +#include <linux/io.h> +#include <linux/spi/spi.h> +#include <linux/spi/spi_bitbang.h> +#include <linux/bitops.h> +#include <linux/gpio.h> + +#include <asm/mach-ath79/ar71xx_regs.h> +#include <asm/mach-ath79/ath79_spi_platform.h> + +#define DRV_NAME "ath79-spi" + +struct ath79_spi { + struct spi_bitbang bitbang; + u32 ioc_base; + u32 reg_ctrl; + void __iomem *base; +}; + +static inline u32 ath79_spi_rr(struct ath79_spi *sp, unsigned reg) +{ + return ioread32(sp->base + reg); +} + +static inline void ath79_spi_wr(struct ath79_spi *sp, unsigned reg, u32 val) +{ + iowrite32(val, sp->base + reg); +} + +static inline struct ath79_spi *ath79_spidev_to_sp(struct spi_device *spi) +{ + return spi_master_get_devdata(spi->master); +} + +static void ath79_spi_chipselect(struct spi_device *spi, int is_active) +{ + struct ath79_spi *sp = ath79_spidev_to_sp(spi); + int cs_high = (spi->mode & SPI_CS_HIGH) ? is_active : !is_active; + + if (is_active) { + /* set initial clock polarity */ + if (spi->mode & SPI_CPOL) + sp->ioc_base |= AR71XX_SPI_IOC_CLK; + else + sp->ioc_base &= ~AR71XX_SPI_IOC_CLK; + + ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, sp->ioc_base); + } + + if (spi->chip_select) { + struct ath79_spi_controller_data *cdata = spi->controller_data; + + /* SPI is normally active-low */ + gpio_set_value(cdata->gpio, cs_high); + } else { + if (cs_high) + sp->ioc_base |= AR71XX_SPI_IOC_CS0; + else + sp->ioc_base &= ~AR71XX_SPI_IOC_CS0; + + ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, sp->ioc_base); + } + +} + +static int ath79_spi_setup_cs(struct spi_device *spi) +{ + struct ath79_spi *sp = ath79_spidev_to_sp(spi); + struct ath79_spi_controller_data *cdata; + + cdata = spi->controller_data; + if (spi->chip_select && !cdata) + return -EINVAL; + + /* enable GPIO mode */ + ath79_spi_wr(sp, AR71XX_SPI_REG_FS, AR71XX_SPI_FS_GPIO); + + /* save CTRL register */ + sp->reg_ctrl = ath79_spi_rr(sp, AR71XX_SPI_REG_CTRL); + sp->ioc_base = ath79_spi_rr(sp, AR71XX_SPI_REG_IOC); + + /* TODO: setup speed? */ + ath79_spi_wr(sp, AR71XX_SPI_REG_CTRL, 0x43); + + if (spi->chip_select) { + int status = 0; + + status = gpio_request(cdata->gpio, dev_name(&spi->dev)); + if (status) + return status; + + status = gpio_direction_output(cdata->gpio, + spi->mode & SPI_CS_HIGH); + if (status) { + gpio_free(cdata->gpio); + return status; + } + } else { + if (spi->mode & SPI_CS_HIGH) + sp->ioc_base |= AR71XX_SPI_IOC_CS0; + else + sp->ioc_base &= ~AR71XX_SPI_IOC_CS0; + ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, sp->ioc_base); + } + + return 0; +} + +static void ath79_spi_cleanup_cs(struct spi_device *spi) +{ + struct ath79_spi *sp = ath79_spidev_to_sp(spi); + + if (spi->chip_select) { + struct ath79_spi_controller_data *cdata = spi->controller_data; + gpio_free(cdata->gpio); + } + + /* restore CTRL register */ + ath79_spi_wr(sp, AR71XX_SPI_REG_CTRL, sp->reg_ctrl); + /* disable GPIO mode */ + ath79_spi_wr(sp, AR71XX_SPI_REG_FS, 0); +} + +static int ath79_spi_setup(struct spi_device *spi) +{ + int status = 0; + + if (spi->bits_per_word > 32) + return -EINVAL; + + if (!spi->controller_state) { + status = ath79_spi_setup_cs(spi); + if (status) + return status; + } + + status = spi_bitbang_setup(spi); + if (status && !spi->controller_state) + ath79_spi_cleanup_cs(spi); + + return status; +} + +static void ath79_spi_cleanup(struct spi_device *spi) +{ + ath79_spi_cleanup_cs(spi); + spi_bitbang_cleanup(spi); +} + +static u32 ath79_spi_txrx_mode0(struct spi_device *spi, unsigned nsecs, + u32 word, u8 bits) +{ + struct ath79_spi *sp = ath79_spidev_to_sp(spi); + u32 ioc = sp->ioc_base; + + /* clock starts at inactive polarity */ + for (word <<= (32 - bits); likely(bits); bits--) { + u32 out; + + if (word & (1 << 31)) + out = ioc | AR71XX_SPI_IOC_DO; + else + out = ioc & ~AR71XX_SPI_IOC_DO; + + /* setup MSB (to slave) on trailing edge */ + ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, out); + ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, out | AR71XX_SPI_IOC_CLK); + + word <<= 1; + } + + return ath79_spi_rr(sp, AR71XX_SPI_REG_RDS); +} + +static __devinit int ath79_spi_probe(struct platform_device *pdev) +{ + struct spi_master *master; + struct ath79_spi *sp; + struct ath79_spi_platform_data *pdata; + struct resource *r; + int ret; + + master = spi_alloc_master(&pdev->dev, sizeof(*sp)); + if (master == NULL) { + dev_err(&pdev->dev, "failed to allocate spi master\n"); + return -ENOMEM; + } + + sp = spi_master_get_devdata(master); + platform_set_drvdata(pdev, sp); + + pdata = pdev->dev.platform_data; + + master->setup = ath79_spi_setup; + master->cleanup = ath79_spi_cleanup; + if (pdata) { + master->bus_num = pdata->bus_num; + master->num_chipselect = pdata->num_chipselect; + } else { + master->bus_num = -1; + master->num_chipselect = 1; + } + + sp->bitbang.master = spi_master_get(master); + sp->bitbang.chipselect = ath79_spi_chipselect; + sp->bitbang.txrx_word[SPI_MODE_0] = ath79_spi_txrx_mode0; + sp->bitbang.setup_transfer = spi_bitbang_setup_transfer; + sp->bitbang.flags = SPI_CS_HIGH; + + r = platform_get_resource(pdev, IORESOURCE_MEM, 0); + if (r == NULL) { + ret = -ENOENT; + goto err_put_master; + } + + sp->base = ioremap(r->start, r->end - r->start + 1); + if (!sp->base) { + ret = -ENXIO; + goto err_put_master; + } + + ret = spi_bitbang_start(&sp->bitbang); + if (ret) + goto err_unmap; + + return 0; + +err_unmap: + iounmap(sp->base); +err_put_master: + platform_set_drvdata(pdev, NULL); + spi_master_put(sp->bitbang.master); + + return ret; +} + +static __devexit int ath79_spi_remove(struct platform_device *pdev) +{ + struct ath79_spi *sp = platform_get_drvdata(pdev); + + spi_bitbang_stop(&sp->bitbang); + iounmap(sp->base); + platform_set_drvdata(pdev, NULL); + spi_master_put(sp->bitbang.master); + + return 0; +} + +static struct platform_driver ath79_spi_driver = { + .probe = ath79_spi_probe, + .remove = __devexit_p(ath79_spi_remove), + .driver = { + .name = DRV_NAME, + .owner = THIS_MODULE, + }, +}; + +static __init int ath79_spi_init(void) +{ + return platform_driver_register(&ath79_spi_driver); +} +module_init(ath79_spi_init); + +static __exit void ath79_spi_exit(void) +{ + platform_driver_unregister(&ath79_spi_driver); +} +module_exit(ath79_spi_exit); + +MODULE_DESCRIPTION("SPI controller driver for Atheros AR71XX/AR724X/AR913X"); +MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>"); +MODULE_LICENSE("GPL v2"); +MODULE_ALIAS("platform:" DRV_NAME); |