/* * i2c Support for Atmel's AT91 Two-Wire Interface (TWI) * * Copyright (C) 2011 Weinmann Medical GmbH * Author: Nikolaus Voss * * Evolved from original work by: * Copyright (C) 2004 Rick Bronson * Converted to 2.6 by Andrew Victor * * Borrowed heavily from original work by: * Copyright (C) 2000 Philip Edelbrock * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. */ #include #include #include #include #include #include #include #include #include #define TWI_CLK_HZ 100000 /* max 400 Kbits/s */ #define AT91_I2C_TIMEOUT msecs_to_jiffies(100) /* transfer timeout */ /* AT91 TWI register definitions */ #define AT91_TWI_CR 0x0000 /* Control Register */ #define AT91_TWI_START 0x0001 /* Send a Start Condition */ #define AT91_TWI_STOP 0x0002 /* Send a Stop Condition */ #define AT91_TWI_MSEN 0x0004 /* Master Transfer Enable */ #define AT91_TWI_SVDIS 0x0020 /* Slave Transfer Disable */ #define AT91_TWI_SWRST 0x0080 /* Software Reset */ #define AT91_TWI_MMR 0x0004 /* Master Mode Register */ #define AT91_TWI_IADRSZ_1 0x0100 /* Internal Device Address Size */ #define AT91_TWI_MREAD 0x1000 /* Master Read Direction */ #define AT91_TWI_IADR 0x000c /* Internal Address Register */ #define AT91_TWI_CWGR 0x0010 /* Clock Waveform Generator Reg */ #define AT91_TWI_SR 0x0020 /* Status Register */ #define AT91_TWI_TXCOMP 0x0001 /* Transmission Complete */ #define AT91_TWI_RXRDY 0x0002 /* Receive Holding Register Ready */ #define AT91_TWI_TXRDY 0x0004 /* Transmit Holding Register Ready */ #define AT91_TWI_OVRE 0x0040 /* Overrun Error */ #define AT91_TWI_UNRE 0x0080 /* Underrun Error */ #define AT91_TWI_NACK 0x0100 /* Not Acknowledged */ #define AT91_TWI_IER 0x0024 /* Interrupt Enable Register */ #define AT91_TWI_IDR 0x0028 /* Interrupt Disable Register */ #define AT91_TWI_IMR 0x002c /* Interrupt Mask Register */ #define AT91_TWI_RHR 0x0030 /* Receive Holding Register */ #define AT91_TWI_THR 0x0034 /* Transmit Holding Register */ struct at91_twi_pdata { unsigned clk_max_div; unsigned clk_offset; bool has_unre_flag; }; struct at91_twi_dev { struct device *dev; void __iomem *base; struct completion cmd_complete; struct clk *clk; u8 *buf; size_t buf_len; struct i2c_msg *msg; int irq; unsigned transfer_status; struct i2c_adapter adapter; unsigned twi_cwgr_reg; struct at91_twi_pdata *pdata; }; static unsigned at91_twi_read(struct at91_twi_dev *dev, unsigned reg) { return readl_relaxed(dev->base + reg); } static void at91_twi_write(struct at91_twi_dev *dev, unsigned reg, unsigned val) { writel_relaxed(val, dev->base + reg); } static void at91_disable_twi_interrupts(struct at91_twi_dev *dev) { at91_twi_write(dev, AT91_TWI_IDR, AT91_TWI_TXCOMP | AT91_TWI_RXRDY | AT91_TWI_TXRDY); } static void at91_init_twi_bus(struct at91_twi_dev *dev) { at91_disable_twi_interrupts(dev); at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_SWRST); at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_MSEN); at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_SVDIS); at91_twi_write(dev, AT91_TWI_CWGR, dev->twi_cwgr_reg); } /* * Calculate symmetric clock as stated in datasheet: * twi_clk = F_MAIN / (2 * (cdiv * (1 << ckdiv) + offset)) */ static void __devinit at91_calc_twi_clock(struct at91_twi_dev *dev, int twi_clk) { int ckdiv, cdiv, div; struct at91_twi_pdata *pdata = dev->pdata; int offset = pdata->clk_offset; int max_ckdiv = pdata->clk_max_div; div = max(0, (int)DIV_ROUND_UP(clk_get_rate(dev->clk), 2 * twi_clk) - offset); ckdiv = fls(div >> 8); cdiv = div >> ckdiv; if (ckdiv > max_ckdiv) { dev_warn(dev->dev, "%d exceeds ckdiv max value which is %d.\n", ckdiv, max_ckdiv); ckdiv = max_ckdiv; cdiv = 255; } dev->twi_cwgr_reg = (ckdiv << 16) | (cdiv << 8) | cdiv; dev_dbg(dev->dev, "cdiv %d ckdiv %d\n", cdiv, ckdiv); } static void at91_twi_write_next_byte(struct at91_twi_dev *dev) { if (dev->buf_len <= 0) return; at91_twi_write(dev, AT91_TWI_THR, *dev->buf); /* send stop when last byte has been written */ if (--dev->buf_len == 0) at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_STOP); dev_dbg(dev->dev, "wrote 0x%x, to go %d\n", *dev->buf, dev->buf_len); ++dev->buf; } static void at91_twi_read_next_byte(struct at91_twi_dev *dev) { if (dev->buf_len <= 0) return; *dev->buf = at91_twi_read(dev, AT91_TWI_RHR) & 0xff; --dev->buf_len; /* handle I2C_SMBUS_BLOCK_DATA */ if (unlikely(dev->msg->flags & I2C_M_RECV_LEN)) { dev->msg->flags &= ~I2C_M_RECV_LEN; dev->buf_len += *dev->buf; dev->msg->len = dev->buf_len + 1; dev_dbg(dev->dev, "received block length %d\n", dev->buf_len); } /* send stop if second but last byte has been read */ if (dev->buf_len == 1) at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_STOP); dev_dbg(dev->dev, "read 0x%x, to go %d\n", *dev->buf, dev->buf_len); ++dev->buf; } static irqreturn_t atmel_twi_interrupt(int irq, void *dev_id) { struct at91_twi_dev *dev = dev_id; const unsigned status = at91_twi_read(dev, AT91_TWI_SR); const unsigned irqstatus = status & at91_twi_read(dev, AT91_TWI_IMR); if (!irqstatus) return IRQ_NONE; else if (irqstatus & AT91_TWI_RXRDY) at91_twi_read_next_byte(dev); else if (irqstatus & AT91_TWI_TXRDY) at91_twi_write_next_byte(dev); /* catch error flags */ dev->transfer_status |= status; if (irqstatus & AT91_TWI_TXCOMP) { at91_disable_twi_interrupts(dev); complete(&dev->cmd_complete); } return IRQ_HANDLED; } static int at91_do_twi_transfer(struct at91_twi_dev *dev) { int ret; bool has_unre_flag = dev->pdata->has_unre_flag; dev_dbg(dev->dev, "transfer: %s %d bytes.\n", (dev->msg->flags & I2C_M_RD) ? "read" : "write", dev->buf_len); INIT_COMPLETION(dev->cmd_complete); dev->transfer_status = 0; if (dev->msg->flags & I2C_M_RD) { unsigned start_flags = AT91_TWI_START; if (at91_twi_read(dev, AT91_TWI_SR) & AT91_TWI_RXRDY) { dev_err(dev->dev, "RXRDY still set!"); at91_twi_read(dev, AT91_TWI_RHR); } /* if only one byte is to be read, immediately stop transfer */ if (dev->buf_len <= 1 && !(dev->msg->flags & I2C_M_RECV_LEN)) start_flags |= AT91_TWI_STOP; at91_twi_write(dev, AT91_TWI_CR, start_flags); at91_twi_write(dev, AT91_TWI_IER, AT91_TWI_TXCOMP | AT91_TWI_RXRDY); } else { at91_twi_write_next_byte(dev); at91_twi_write(dev, AT91_TWI_IER, AT91_TWI_TXCOMP | AT91_TWI_TXRDY); } ret = wait_for_completion_interruptible_timeout(&dev->cmd_complete, dev->adapter.timeout); if (ret == 0) { dev_err(dev->dev, "controller timed out\n"); at91_init_twi_bus(dev); return -ETIMEDOUT; } if (dev->transfer_status & AT91_TWI_NACK) { dev_dbg(dev->dev, "received nack\n"); return -EREMOTEIO; } if (dev->transfer_status & AT91_TWI_OVRE) { dev_err(dev->dev, "overrun while reading\n"); return -EIO; } if (has_unre_flag && dev->transfer_status & AT91_TWI_UNRE) { dev_err(dev->dev, "underrun while writing\n"); return -EIO; } dev_dbg(dev->dev, "transfer complete\n"); return 0; } static int at91_twi_xfer(struct i2c_adapter *adap, struct i2c_msg *msg, int num) { struct at91_twi_dev *dev = i2c_get_adapdata(adap); int ret; unsigned int_addr_flag = 0; struct i2c_msg *m_start = msg; dev_dbg(&adap->dev, "at91_xfer: processing %d messages:\n", num); /* * The hardware can handle at most two messages concatenated by a * repeated start via it's internal address feature. */ if (num > 2) { dev_err(dev->dev, "cannot handle more than two concatenated messages.\n"); return 0; } else if (num == 2) { int internal_address = 0; int i; if (msg->flags & I2C_M_RD) { dev_err(dev->dev, "first transfer must be write.\n"); return -EINVAL; } if (msg->len > 3) { dev_err(dev->dev, "first message size must be <= 3.\n"); return -EINVAL; } /* 1st msg is put into the internal address, start with 2nd */ m_start = &msg[1]; for (i = 0; i < msg->len; ++i) { const unsigned addr = msg->buf[msg->len - 1 - i]; internal_address |= addr << (8 * i); int_addr_flag += AT91_TWI_IADRSZ_1; } at91_twi_write(dev, AT91_TWI_IADR, internal_address); } at91_twi_write(dev, AT91_TWI_MMR, (m_start->addr << 16) | int_addr_flag | ((m_start->flags & I2C_M_RD) ? AT91_TWI_MREAD : 0)); dev->buf_len = m_start->len; dev->buf = m_start->buf; dev->msg = m_start; ret = at91_do_twi_transfer(dev); return (ret < 0) ? ret : num; } static u32 at91_twi_func(struct i2c_adapter *adapter) { return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_SMBUS_READ_BLOCK_DATA; } static struct i2c_algorithm at91_twi_algorithm = { .master_xfer = at91_twi_xfer, .functionality = at91_twi_func, }; static struct at91_twi_pdata at91rm9200_config = { .clk_max_div = 5, .clk_offset = 3, .has_unre_flag = true, }; static struct at91_twi_pdata at91sam9261_config = { .clk_max_div = 5, .clk_offset = 4, .has_unre_flag = false, }; static struct at91_twi_pdata at91sam9260_config = { .clk_max_div = 7, .clk_offset = 4, .has_unre_flag = false, }; static struct at91_twi_pdata at91sam9g20_config = { .clk_max_div = 7, .clk_offset = 4, .has_unre_flag = false, }; static struct at91_twi_pdata at91sam9g10_config = { .clk_max_div = 7, .clk_offset = 4, .has_unre_flag = false, }; static const struct platform_device_id at91_twi_devtypes[] = { { .name = "i2c-at91rm9200", .driver_data = (unsigned long) &at91rm9200_config, }, { .name = "i2c-at91sam9261", .driver_data = (unsigned long) &at91sam9261_config, }, { .name = "i2c-at91sam9260", .driver_data = (unsigned long) &at91sam9260_config, }, { .name = "i2c-at91sam9g20", .driver_data = (unsigned long) &at91sam9g20_config, }, { .name = "i2c-at91sam9g10", .driver_data = (unsigned long) &at91sam9g10_config, }, { /* sentinel */ } }; static int __devinit at91_twi_probe(struct platform_device *pdev) { struct at91_twi_dev *dev; struct resource *mem; int rc; dev = devm_kzalloc(&pdev->dev, sizeof(*dev), GFP_KERNEL); if (!dev) return -ENOMEM; init_completion(&dev->cmd_complete); dev->dev = &pdev->dev; mem = platform_get_resource(pdev, IORESOURCE_MEM, 0); if (!mem) return -ENODEV; dev->pdata = at91_twi_get_driver_data(pdev); if (!dev->pdata) return -ENODEV; dev->base = devm_request_and_ioremap(&pdev->dev, mem); if (!dev->base) return -EBUSY; dev->irq = platform_get_irq(pdev, 0); if (dev->irq < 0) return dev->irq; rc = devm_request_irq(&pdev->dev, dev->irq, atmel_twi_interrupt, 0, dev_name(dev->dev), dev); if (rc) { dev_err(dev->dev, "Cannot get irq %d: %d\n", dev->irq, rc); return rc; } platform_set_drvdata(pdev, dev); dev->clk = devm_clk_get(dev->dev, NULL); if (IS_ERR(dev->clk)) { dev_err(dev->dev, "no clock defined\n"); return -ENODEV; } clk_prepare_enable(dev->clk); at91_calc_twi_clock(dev, TWI_CLK_HZ); at91_init_twi_bus(dev); snprintf(dev->adapter.name, sizeof(dev->adapter.name), "AT91"); i2c_set_adapdata(&dev->adapter, dev); dev->adapter.owner = THIS_MODULE; dev->adapter.class = I2C_CLASS_HWMON; dev->adapter.algo = &at91_twi_algorithm; dev->adapter.dev.parent = dev->dev; dev->adapter.nr = pdev->id; dev->adapter.timeout = AT91_I2C_TIMEOUT; rc = i2c_add_numbered_adapter(&dev->adapter); if (rc) { dev_err(dev->dev, "Adapter %s registration failed\n", dev->adapter.name); clk_disable_unprepare(dev->clk); return rc; } dev_info(dev->dev, "AT91 i2c bus driver.\n"); return 0; } static int __devexit at91_twi_remove(struct platform_device *pdev) { struct at91_twi_dev *dev = platform_get_drvdata(pdev); int rc; rc = i2c_del_adapter(&dev->adapter); clk_disable_unprepare(dev->clk); return rc; } #ifdef CONFIG_PM static int at91_twi_runtime_suspend(struct device *dev) { struct at91_twi_dev *twi_dev = dev_get_drvdata(dev); clk_disable(twi_dev->clk); return 0; } static int at91_twi_runtime_resume(struct device *dev) { struct at91_twi_dev *twi_dev = dev_get_drvdata(dev); return clk_enable(twi_dev->clk); } static const struct dev_pm_ops at91_twi_pm = { .runtime_suspend = at91_twi_runtime_suspend, .runtime_resume = at91_twi_runtime_resume, }; #define at91_twi_pm_ops (&at91_twi_pm) #else #define at91_twi_pm_ops NULL #endif static struct platform_driver at91_twi_driver = { .probe = at91_twi_probe, .remove = __devexit_p(at91_twi_remove), .id_table = at91_twi_devtypes, .driver = { .name = "at91_i2c", .owner = THIS_MODULE, .pm = at91_twi_pm_ops, }, }; static int __init at91_twi_init(void) { return platform_driver_register(&at91_twi_driver); } static void __exit at91_twi_exit(void) { platform_driver_unregister(&at91_twi_driver); } subsys_initcall(at91_twi_init); module_exit(at91_twi_exit); MODULE_AUTHOR("Nikolaus Voss "); MODULE_DESCRIPTION("I2C (TWI) driver for Atmel AT91"); MODULE_LICENSE("GPL"); MODULE_ALIAS("platform:at91_i2c");