/* * 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 = SPI_BPW_MASK(8); 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");