/* * Xtensa xtfpga SPI controller driver * * Copyright (c) 2014 Cadence Design Systems Inc. * * 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/delay.h> #include <linux/io.h> #include <linux/module.h> #include <linux/of.h> #include <linux/platform_device.h> #include <linux/spi/spi.h> #include <linux/spi/spi_bitbang.h> #define XTFPGA_SPI_NAME "xtfpga_spi" #define XTFPGA_SPI_START 0x0 #define XTFPGA_SPI_BUSY 0x4 #define XTFPGA_SPI_DATA 0x8 #define BUSY_WAIT_US 100 struct xtfpga_spi { struct spi_bitbang bitbang; void __iomem *regs; u32 data; unsigned data_sz; }; static inline void xtfpga_spi_write32(const struct xtfpga_spi *spi, unsigned addr, u32 val) { iowrite32(val, spi->regs + addr); } static inline unsigned int xtfpga_spi_read32(const struct xtfpga_spi *spi, unsigned addr) { return ioread32(spi->regs + addr); } static inline void xtfpga_spi_wait_busy(struct xtfpga_spi *xspi) { unsigned i; for (i = 0; xtfpga_spi_read32(xspi, XTFPGA_SPI_BUSY) && i < BUSY_WAIT_US; ++i) udelay(1); WARN_ON_ONCE(i == BUSY_WAIT_US); } static u32 xtfpga_spi_txrx_word(struct spi_device *spi, unsigned nsecs, u32 v, u8 bits) { struct xtfpga_spi *xspi = spi_master_get_devdata(spi->master); xspi->data = (xspi->data << bits) | (v & GENMASK(bits - 1, 0)); xspi->data_sz += bits; if (xspi->data_sz >= 16) { xtfpga_spi_write32(xspi, XTFPGA_SPI_DATA, xspi->data >> (xspi->data_sz - 16)); xspi->data_sz -= 16; xtfpga_spi_write32(xspi, XTFPGA_SPI_START, 1); xtfpga_spi_wait_busy(xspi); xtfpga_spi_write32(xspi, XTFPGA_SPI_START, 0); } return 0; } static void xtfpga_spi_chipselect(struct spi_device *spi, int is_on) { struct xtfpga_spi *xspi = spi_master_get_devdata(spi->master); WARN_ON(xspi->data_sz != 0); xspi->data_sz = 0; } static int xtfpga_spi_probe(struct platform_device *pdev) { struct xtfpga_spi *xspi; struct resource *mem; int ret; struct spi_master *master; master = spi_alloc_master(&pdev->dev, sizeof(struct xtfpga_spi)); if (!master) return -ENOMEM; master->flags = SPI_MASTER_NO_RX; master->bits_per_word_mask = SPI_BPW_RANGE_MASK(1, 16); master->bus_num = pdev->dev.id; master->dev.of_node = pdev->dev.of_node; xspi = spi_master_get_devdata(master); xspi->bitbang.master = master; xspi->bitbang.chipselect = xtfpga_spi_chipselect; xspi->bitbang.txrx_word[SPI_MODE_0] = xtfpga_spi_txrx_word; mem = platform_get_resource(pdev, IORESOURCE_MEM, 0); if (!mem) { dev_err(&pdev->dev, "No memory resource\n"); ret = -ENODEV; goto err; } xspi->regs = devm_ioremap_resource(&pdev->dev, mem); if (IS_ERR(xspi->regs)) { ret = PTR_ERR(xspi->regs); goto err; } xtfpga_spi_write32(xspi, XTFPGA_SPI_START, 0); usleep_range(1000, 2000); if (xtfpga_spi_read32(xspi, XTFPGA_SPI_BUSY)) { dev_err(&pdev->dev, "Device stuck in busy state\n"); ret = -EBUSY; goto err; } ret = spi_bitbang_start(&xspi->bitbang); if (ret < 0) { dev_err(&pdev->dev, "spi_bitbang_start failed\n"); goto err; } platform_set_drvdata(pdev, master); return 0; err: spi_master_put(master); return ret; } static int xtfpga_spi_remove(struct platform_device *pdev) { struct spi_master *master = platform_get_drvdata(pdev); struct xtfpga_spi *xspi = spi_master_get_devdata(master); spi_bitbang_stop(&xspi->bitbang); spi_master_put(master); return 0; } MODULE_ALIAS("platform:" XTFPGA_SPI_NAME); #ifdef CONFIG_OF static const struct of_device_id xtfpga_spi_of_match[] = { { .compatible = "cdns,xtfpga-spi", }, {} }; MODULE_DEVICE_TABLE(of, xtfpga_spi_of_match); #endif static struct platform_driver xtfpga_spi_driver = { .probe = xtfpga_spi_probe, .remove = xtfpga_spi_remove, .driver = { .name = XTFPGA_SPI_NAME, .owner = THIS_MODULE, .of_match_table = of_match_ptr(xtfpga_spi_of_match), }, }; module_platform_driver(xtfpga_spi_driver); MODULE_AUTHOR("Max Filippov <jcmvbkbc@gmail.com>"); MODULE_DESCRIPTION("xtensa xtfpga SPI driver"); MODULE_LICENSE("GPL");