// SPDX-License-Identifier: GPL-2.0-only /* * OpenCores tiny SPI host driver * * https://opencores.org/project,tiny_spi * * Copyright (C) 2011 Thomas Chou <thomas@wytron.com.tw> * * Based on spi_s3c24xx.c, which is: * Copyright (c) 2006 Ben Dooks * Copyright (c) 2006 Simtec Electronics * Ben Dooks <ben@simtec.co.uk> */ #include <linux/interrupt.h> #include <linux/errno.h> #include <linux/module.h> #include <linux/platform_device.h> #include <linux/spi/spi.h> #include <linux/spi/spi_bitbang.h> #include <linux/spi/spi_oc_tiny.h> #include <linux/io.h> #include <linux/of.h> #define DRV_NAME "spi_oc_tiny" #define TINY_SPI_RXDATA 0 #define TINY_SPI_TXDATA 4 #define TINY_SPI_STATUS 8 #define TINY_SPI_CONTROL 12 #define TINY_SPI_BAUD 16 #define TINY_SPI_STATUS_TXE 0x1 #define TINY_SPI_STATUS_TXR 0x2 struct tiny_spi { /* bitbang has to be first */ struct spi_bitbang bitbang; struct completion done; void __iomem *base; int irq; unsigned int freq; unsigned int baudwidth; unsigned int baud; unsigned int speed_hz; unsigned int mode; unsigned int len; unsigned int txc, rxc; const u8 *txp; u8 *rxp; }; static inline struct tiny_spi *tiny_spi_to_hw(struct spi_device *sdev) { return spi_controller_get_devdata(sdev->controller); } static unsigned int tiny_spi_baud(struct spi_device *spi, unsigned int hz) { struct tiny_spi *hw = tiny_spi_to_hw(spi); return min(DIV_ROUND_UP(hw->freq, hz * 2), (1U << hw->baudwidth)) - 1; } static int tiny_spi_setup_transfer(struct spi_device *spi, struct spi_transfer *t) { struct tiny_spi *hw = tiny_spi_to_hw(spi); unsigned int baud = hw->baud; if (t) { if (t->speed_hz && t->speed_hz != hw->speed_hz) baud = tiny_spi_baud(spi, t->speed_hz); } writel(baud, hw->base + TINY_SPI_BAUD); writel(hw->mode, hw->base + TINY_SPI_CONTROL); return 0; } static int tiny_spi_setup(struct spi_device *spi) { struct tiny_spi *hw = tiny_spi_to_hw(spi); if (spi->max_speed_hz != hw->speed_hz) { hw->speed_hz = spi->max_speed_hz; hw->baud = tiny_spi_baud(spi, hw->speed_hz); } hw->mode = spi->mode & SPI_MODE_X_MASK; return 0; } static inline void tiny_spi_wait_txr(struct tiny_spi *hw) { while (!(readb(hw->base + TINY_SPI_STATUS) & TINY_SPI_STATUS_TXR)) cpu_relax(); } static inline void tiny_spi_wait_txe(struct tiny_spi *hw) { while (!(readb(hw->base + TINY_SPI_STATUS) & TINY_SPI_STATUS_TXE)) cpu_relax(); } static int tiny_spi_txrx_bufs(struct spi_device *spi, struct spi_transfer *t) { struct tiny_spi *hw = tiny_spi_to_hw(spi); const u8 *txp = t->tx_buf; u8 *rxp = t->rx_buf; unsigned int i; if (hw->irq >= 0) { /* use interrupt driven data transfer */ hw->len = t->len; hw->txp = t->tx_buf; hw->rxp = t->rx_buf; hw->txc = 0; hw->rxc = 0; /* send the first byte */ if (t->len > 1) { writeb(hw->txp ? *hw->txp++ : 0, hw->base + TINY_SPI_TXDATA); hw->txc++; writeb(hw->txp ? *hw->txp++ : 0, hw->base + TINY_SPI_TXDATA); hw->txc++; writeb(TINY_SPI_STATUS_TXR, hw->base + TINY_SPI_STATUS); } else { writeb(hw->txp ? *hw->txp++ : 0, hw->base + TINY_SPI_TXDATA); hw->txc++; writeb(TINY_SPI_STATUS_TXE, hw->base + TINY_SPI_STATUS); } wait_for_completion(&hw->done); } else { /* we need to tighten the transfer loop */ writeb(txp ? *txp++ : 0, hw->base + TINY_SPI_TXDATA); for (i = 1; i < t->len; i++) { writeb(txp ? *txp++ : 0, hw->base + TINY_SPI_TXDATA); if (rxp || (i != t->len - 1)) tiny_spi_wait_txr(hw); if (rxp) *rxp++ = readb(hw->base + TINY_SPI_TXDATA); } tiny_spi_wait_txe(hw); if (rxp) *rxp++ = readb(hw->base + TINY_SPI_RXDATA); } return t->len; } static irqreturn_t tiny_spi_irq(int irq, void *dev) { struct tiny_spi *hw = dev; writeb(0, hw->base + TINY_SPI_STATUS); if (hw->rxc + 1 == hw->len) { if (hw->rxp) *hw->rxp++ = readb(hw->base + TINY_SPI_RXDATA); hw->rxc++; complete(&hw->done); } else { if (hw->rxp) *hw->rxp++ = readb(hw->base + TINY_SPI_TXDATA); hw->rxc++; if (hw->txc < hw->len) { writeb(hw->txp ? *hw->txp++ : 0, hw->base + TINY_SPI_TXDATA); hw->txc++; writeb(TINY_SPI_STATUS_TXR, hw->base + TINY_SPI_STATUS); } else { writeb(TINY_SPI_STATUS_TXE, hw->base + TINY_SPI_STATUS); } } return IRQ_HANDLED; } #ifdef CONFIG_OF #include <linux/of_gpio.h> static int tiny_spi_of_probe(struct platform_device *pdev) { struct tiny_spi *hw = platform_get_drvdata(pdev); struct device_node *np = pdev->dev.of_node; u32 val; if (!np) return 0; hw->bitbang.ctlr->dev.of_node = pdev->dev.of_node; if (!of_property_read_u32(np, "clock-frequency", &val)) hw->freq = val; if (!of_property_read_u32(np, "baud-width", &val)) hw->baudwidth = val; return 0; } #else /* !CONFIG_OF */ static int tiny_spi_of_probe(struct platform_device *pdev) { return 0; } #endif /* CONFIG_OF */ static int tiny_spi_probe(struct platform_device *pdev) { struct tiny_spi_platform_data *platp = dev_get_platdata(&pdev->dev); struct tiny_spi *hw; struct spi_controller *host; int err = -ENODEV; host = spi_alloc_host(&pdev->dev, sizeof(struct tiny_spi)); if (!host) return err; /* setup the host state. */ host->bus_num = pdev->id; host->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH; host->setup = tiny_spi_setup; host->use_gpio_descriptors = true; hw = spi_controller_get_devdata(host); platform_set_drvdata(pdev, hw); /* setup the state for the bitbang driver */ hw->bitbang.ctlr = host; hw->bitbang.setup_transfer = tiny_spi_setup_transfer; hw->bitbang.txrx_bufs = tiny_spi_txrx_bufs; /* find and map our resources */ hw->base = devm_platform_ioremap_resource(pdev, 0); if (IS_ERR(hw->base)) { err = PTR_ERR(hw->base); goto exit; } /* irq is optional */ hw->irq = platform_get_irq(pdev, 0); if (hw->irq >= 0) { init_completion(&hw->done); err = devm_request_irq(&pdev->dev, hw->irq, tiny_spi_irq, 0, pdev->name, hw); if (err) goto exit; } /* find platform data */ if (platp) { hw->freq = platp->freq; hw->baudwidth = platp->baudwidth; } else { err = tiny_spi_of_probe(pdev); if (err) goto exit; } /* register our spi controller */ err = spi_bitbang_start(&hw->bitbang); if (err) goto exit; dev_info(&pdev->dev, "base %p, irq %d\n", hw->base, hw->irq); return 0; exit: spi_controller_put(host); return err; } static void tiny_spi_remove(struct platform_device *pdev) { struct tiny_spi *hw = platform_get_drvdata(pdev); struct spi_controller *host = hw->bitbang.ctlr; spi_bitbang_stop(&hw->bitbang); spi_controller_put(host); } #ifdef CONFIG_OF static const struct of_device_id tiny_spi_match[] = { { .compatible = "opencores,tiny-spi-rtlsvn2", }, {}, }; MODULE_DEVICE_TABLE(of, tiny_spi_match); #endif /* CONFIG_OF */ static struct platform_driver tiny_spi_driver = { .probe = tiny_spi_probe, .remove_new = tiny_spi_remove, .driver = { .name = DRV_NAME, .pm = NULL, .of_match_table = of_match_ptr(tiny_spi_match), }, }; module_platform_driver(tiny_spi_driver); MODULE_DESCRIPTION("OpenCores tiny SPI driver"); MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>"); MODULE_LICENSE("GPL"); MODULE_ALIAS("platform:" DRV_NAME);