diff options
Diffstat (limited to 'kernel/drivers/spi/spi-rb4xx.c')
| -rw-r--r-- | kernel/drivers/spi/spi-rb4xx.c | 210 |
1 files changed, 210 insertions, 0 deletions
diff --git a/kernel/drivers/spi/spi-rb4xx.c b/kernel/drivers/spi/spi-rb4xx.c new file mode 100644 index 000000000..3641d0e20 --- /dev/null +++ b/kernel/drivers/spi/spi-rb4xx.c @@ -0,0 +1,210 @@ +/* + * SPI controller driver for the Mikrotik RB4xx boards + * + * Copyright (C) 2010 Gabor Juhos <juhosg@openwrt.org> + * Copyright (C) 2015 Bert Vermeulen <bert@biot.com> + * + * This file was based on the patches for Linux 2.6.27.39 published by + * MikroTik for their RouterBoard 4xx series devices. + * + * 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/module.h> +#include <linux/platform_device.h> +#include <linux/clk.h> +#include <linux/spi/spi.h> + +#include <asm/mach-ath79/ar71xx_regs.h> + +struct rb4xx_spi { + void __iomem *base; + struct clk *clk; +}; + +static inline u32 rb4xx_read(struct rb4xx_spi *rbspi, u32 reg) +{ + return __raw_readl(rbspi->base + reg); +} + +static inline void rb4xx_write(struct rb4xx_spi *rbspi, u32 reg, u32 value) +{ + __raw_writel(value, rbspi->base + reg); +} + +static inline void do_spi_clk(struct rb4xx_spi *rbspi, u32 spi_ioc, int value) +{ + u32 regval; + + regval = spi_ioc; + if (value & BIT(0)) + regval |= AR71XX_SPI_IOC_DO; + + rb4xx_write(rbspi, AR71XX_SPI_REG_IOC, regval); + rb4xx_write(rbspi, AR71XX_SPI_REG_IOC, regval | AR71XX_SPI_IOC_CLK); +} + +static void do_spi_byte(struct rb4xx_spi *rbspi, u32 spi_ioc, u8 byte) +{ + int i; + + for (i = 7; i >= 0; i--) + do_spi_clk(rbspi, spi_ioc, byte >> i); +} + +/* The CS2 pin is used to clock in a second bit per clock cycle. */ +static inline void do_spi_clk_two(struct rb4xx_spi *rbspi, u32 spi_ioc, + u8 value) +{ + u32 regval; + + regval = spi_ioc; + if (value & BIT(1)) + regval |= AR71XX_SPI_IOC_DO; + if (value & BIT(0)) + regval |= AR71XX_SPI_IOC_CS2; + + rb4xx_write(rbspi, AR71XX_SPI_REG_IOC, regval); + rb4xx_write(rbspi, AR71XX_SPI_REG_IOC, regval | AR71XX_SPI_IOC_CLK); +} + +/* Two bits at a time, msb first */ +static void do_spi_byte_two(struct rb4xx_spi *rbspi, u32 spi_ioc, u8 byte) +{ + do_spi_clk_two(rbspi, spi_ioc, byte >> 6); + do_spi_clk_two(rbspi, spi_ioc, byte >> 4); + do_spi_clk_two(rbspi, spi_ioc, byte >> 2); + do_spi_clk_two(rbspi, spi_ioc, byte >> 0); +} + +static void rb4xx_set_cs(struct spi_device *spi, bool enable) +{ + struct rb4xx_spi *rbspi = spi_master_get_devdata(spi->master); + + /* + * Setting CS is done along with bitbanging the actual values, + * since it's all on the same hardware register. However the + * CPLD needs CS deselected after every command. + */ + if (enable) + rb4xx_write(rbspi, AR71XX_SPI_REG_IOC, + AR71XX_SPI_IOC_CS0 | AR71XX_SPI_IOC_CS1); +} + +static int rb4xx_transfer_one(struct spi_master *master, + struct spi_device *spi, struct spi_transfer *t) +{ + struct rb4xx_spi *rbspi = spi_master_get_devdata(master); + int i; + u32 spi_ioc; + u8 *rx_buf; + const u8 *tx_buf; + + /* + * Prime the SPI register with the SPI device selected. The m25p80 boot + * flash and CPLD share the CS0 pin. This works because the CPLD's + * command set was designed to almost not clash with that of the + * boot flash. + */ + if (spi->chip_select == 2) + /* MMC */ + spi_ioc = AR71XX_SPI_IOC_CS0; + else + /* Boot flash and CPLD */ + spi_ioc = AR71XX_SPI_IOC_CS1; + + tx_buf = t->tx_buf; + rx_buf = t->rx_buf; + for (i = 0; i < t->len; ++i) { + if (t->tx_nbits == SPI_NBITS_DUAL) + /* CPLD can use two-wire transfers */ + do_spi_byte_two(rbspi, spi_ioc, tx_buf[i]); + else + do_spi_byte(rbspi, spi_ioc, tx_buf[i]); + if (!rx_buf) + continue; + rx_buf[i] = rb4xx_read(rbspi, AR71XX_SPI_REG_RDS); + } + spi_finalize_current_transfer(master); + + return 0; +} + +static int rb4xx_spi_probe(struct platform_device *pdev) +{ + struct spi_master *master; + struct clk *ahb_clk; + struct rb4xx_spi *rbspi; + struct resource *r; + int err; + void __iomem *spi_base; + + r = platform_get_resource(pdev, IORESOURCE_MEM, 0); + spi_base = devm_ioremap_resource(&pdev->dev, r); + if (IS_ERR(spi_base)) + return PTR_ERR(spi_base); + + master = spi_alloc_master(&pdev->dev, sizeof(*rbspi)); + if (!master) + return -ENOMEM; + + ahb_clk = devm_clk_get(&pdev->dev, "ahb"); + if (IS_ERR(ahb_clk)) + return PTR_ERR(ahb_clk); + + master->bus_num = 0; + master->num_chipselect = 3; + master->mode_bits = SPI_TX_DUAL; + master->bits_per_word_mask = BIT(7); + master->flags = SPI_MASTER_MUST_TX; + master->transfer_one = rb4xx_transfer_one; + master->set_cs = rb4xx_set_cs; + + err = devm_spi_register_master(&pdev->dev, master); + if (err) { + dev_err(&pdev->dev, "failed to register SPI master\n"); + return err; + } + + err = clk_prepare_enable(ahb_clk); + if (err) + return err; + + rbspi = spi_master_get_devdata(master); + rbspi->base = spi_base; + rbspi->clk = ahb_clk; + platform_set_drvdata(pdev, rbspi); + + /* Enable SPI */ + rb4xx_write(rbspi, AR71XX_SPI_REG_FS, AR71XX_SPI_FS_GPIO); + + return 0; +} + +static int rb4xx_spi_remove(struct platform_device *pdev) +{ + struct rb4xx_spi *rbspi = platform_get_drvdata(pdev); + + clk_disable_unprepare(rbspi->clk); + + return 0; +} + +static struct platform_driver rb4xx_spi_drv = { + .probe = rb4xx_spi_probe, + .remove = rb4xx_spi_remove, + .driver = { + .name = "rb4xx-spi", + }, +}; + +module_platform_driver(rb4xx_spi_drv); + +MODULE_DESCRIPTION("Mikrotik RB4xx SPI controller driver"); +MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>"); +MODULE_AUTHOR("Bert Vermeulen <bert@biot.com>"); +MODULE_LICENSE("GPL v2"); |