/* * 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 #include #include #include #include #include #define DEFAULT_TWI_CLK_HZ 100000 /* max 400 Kbits/s */ #define AT91_I2C_TIMEOUT msecs_to_jiffies(100) /* transfer timeout */ #define AT91_I2C_DMA_THRESHOLD 8 /* enable DMA if transfer size is bigger than this threshold */ /* 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_QUICK 0x0040 /* SMBus quick command */ #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; bool has_dma_support; struct at_dma_slave dma_slave; }; struct at91_twi_dma { struct dma_chan *chan_rx; struct dma_chan *chan_tx; struct scatterlist sg; struct dma_async_tx_descriptor *data_desc; enum dma_data_direction direction; bool buf_mapped; bool xfer_in_progress; }; 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 imr; unsigned transfer_status; struct i2c_adapter adapter; unsigned twi_cwgr_reg; struct at91_twi_pdata *pdata; bool use_dma; struct at91_twi_dma dma; }; 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_twi_irq_save(struct at91_twi_dev *dev) { dev->imr = at91_twi_read(dev, AT91_TWI_IMR) & 0x7; at91_disable_twi_interrupts(dev); } static void at91_twi_irq_restore(struct at91_twi_dev *dev) { at91_twi_write(dev, AT91_TWI_IER, dev->imr); } 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 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_dma_cleanup(struct at91_twi_dev *dev) { struct at91_twi_dma *dma = &dev->dma; at91_twi_irq_save(dev); if (dma->xfer_in_progress) { if (dma->direction == DMA_FROM_DEVICE) dmaengine_terminate_all(dma->chan_rx); else dmaengine_terminate_all(dma->chan_tx); dma->xfer_in_progress = false; } if (dma->buf_mapped) { dma_unmap_single(dev->dev, sg_dma_address(&dma->sg), dev->buf_len, dma->direction); dma->buf_mapped = false; } at91_twi_irq_restore(dev); } 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_write_data_dma_callback(void *data) { struct at91_twi_dev *dev = (struct at91_twi_dev *)data; dma_unmap_single(dev->dev, sg_dma_address(&dev->dma.sg), dev->buf_len, DMA_TO_DEVICE); at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_STOP); } static void at91_twi_write_data_dma(struct at91_twi_dev *dev) { dma_addr_t dma_addr; struct dma_async_tx_descriptor *txdesc; struct at91_twi_dma *dma = &dev->dma; struct dma_chan *chan_tx = dma->chan_tx; if (dev->buf_len <= 0) return; dma->direction = DMA_TO_DEVICE; at91_twi_irq_save(dev); dma_addr = dma_map_single(dev->dev, dev->buf, dev->buf_len, DMA_TO_DEVICE); if (dma_mapping_error(dev->dev, dma_addr)) { dev_err(dev->dev, "dma map failed\n"); return; } dma->buf_mapped = true; at91_twi_irq_restore(dev); sg_dma_len(&dma->sg) = dev->buf_len; sg_dma_address(&dma->sg) = dma_addr; txdesc = dmaengine_prep_slave_sg(chan_tx, &dma->sg, 1, DMA_MEM_TO_DEV, DMA_PREP_INTERRUPT | DMA_CTRL_ACK); if (!txdesc) { dev_err(dev->dev, "dma prep slave sg failed\n"); goto error; } txdesc->callback = at91_twi_write_data_dma_callback; txdesc->callback_param = dev; dma->xfer_in_progress = true; dmaengine_submit(txdesc); dma_async_issue_pending(chan_tx); return; error: at91_twi_dma_cleanup(dev); } 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 void at91_twi_read_data_dma_callback(void *data) { struct at91_twi_dev *dev = (struct at91_twi_dev *)data; dma_unmap_single(dev->dev, sg_dma_address(&dev->dma.sg), dev->buf_len, DMA_FROM_DEVICE); /* The last two bytes have to be read without using dma */ dev->buf += dev->buf_len - 2; dev->buf_len = 2; at91_twi_write(dev, AT91_TWI_IER, AT91_TWI_RXRDY); } static void at91_twi_read_data_dma(struct at91_twi_dev *dev) { dma_addr_t dma_addr; struct dma_async_tx_descriptor *rxdesc; struct at91_twi_dma *dma = &dev->dma; struct dma_chan *chan_rx = dma->chan_rx; dma->direction = DMA_FROM_DEVICE; /* Keep in mind that we won't use dma to read the last two bytes */ at91_twi_irq_save(dev); dma_addr = dma_map_single(dev->dev, dev->buf, dev->buf_len - 2, DMA_FROM_DEVICE); if (dma_mapping_error(dev->dev, dma_addr)) { dev_err(dev->dev, "dma map failed\n"); return; } dma->buf_mapped = true; at91_twi_irq_restore(dev); dma->sg.dma_address = dma_addr; sg_dma_len(&dma->sg) = dev->buf_len - 2; rxdesc = dmaengine_prep_slave_sg(chan_rx, &dma->sg, 1, DMA_DEV_TO_MEM, DMA_PREP_INTERRUPT | DMA_CTRL_ACK); if (!rxdesc) { dev_err(dev->dev, "dma prep slave sg failed\n"); goto error; } rxdesc->callback = at91_twi_read_data_dma_callback; rxdesc->callback_param = dev; dma->xfer_in_progress = true; dmaengine_submit(rxdesc); dma_async_issue_pending(dma->chan_rx); return; error: at91_twi_dma_cleanup(dev); } 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); reinit_completion(&dev->cmd_complete); dev->transfer_status = 0; if (!dev->buf_len) { at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_QUICK); at91_twi_write(dev, AT91_TWI_IER, AT91_TWI_TXCOMP); } else 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); /* * When using dma, the last byte has to be read manually in * order to not send the stop command too late and then * to receive extra data. In practice, there are some issues * if you use the dma to read n-1 bytes because of latency. * Reading n-2 bytes with dma and the two last ones manually * seems to be the best solution. */ if (dev->use_dma && (dev->buf_len > AT91_I2C_DMA_THRESHOLD)) { at91_twi_read_data_dma(dev); /* * It is important to enable TXCOMP irq here because * doing it only when transferring the last two bytes * will mask NACK errors since TXCOMP is set when a * NACK occurs. */ at91_twi_write(dev, AT91_TWI_IER, AT91_TWI_TXCOMP); } else at91_twi_write(dev, AT91_TWI_IER, AT91_TWI_TXCOMP | AT91_TWI_RXRDY); } else { if (dev->use_dma && (dev->buf_len > AT91_I2C_DMA_THRESHOLD)) { at91_twi_write_data_dma(dev); at91_twi_write(dev, AT91_TWI_IER, AT91_TWI_TXCOMP); } else { at91_twi_write_next_byte(dev); at91_twi_write(dev, AT91_TWI_IER, AT91_TWI_TXCOMP | AT91_TWI_TXRDY); } } ret = wait_for_completion_io_timeout(&dev->cmd_complete, dev->adapter.timeout); if (ret == 0) { dev_err(dev->dev, "controller timed out\n"); at91_init_twi_bus(dev); ret = -ETIMEDOUT; goto error; } if (dev->transfer_status & AT91_TWI_NACK) { dev_dbg(dev->dev, "received nack\n"); ret = -EREMOTEIO; goto error; } if (dev->transfer_status & AT91_TWI_OVRE) { dev_err(dev->dev, "overrun while reading\n"); ret = -EIO; goto error; } if (has_unre_flag && dev->transfer_status & AT91_TWI_UNRE) { dev_err(dev->dev, "underrun while writing\n"); ret = -EIO; goto error; } dev_dbg(dev->dev, "transfer complete\n"); return 0; error: at91_twi_dma_cleanup(dev); return ret; } 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, .has_dma_support = false, }; static struct at91_twi_pdata at91sam9261_config = { .clk_max_div = 5, .clk_offset = 4, .has_unre_flag = false, .has_dma_support = false, }; static struct at91_twi_pdata at91sam9260_config = { .clk_max_div = 7, .clk_offset = 4, .has_unre_flag = false, .has_dma_support = false, }; static struct at91_twi_pdata at91sam9g20_config = { .clk_max_div = 7, .clk_offset = 4, .has_unre_flag = false, .has_dma_support = false, }; static struct at91_twi_pdata at91sam9g10_config = { .clk_max_div = 7, .clk_offset = 4, .has_unre_flag = false, .has_dma_support = 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 */ } }; #if defined(CONFIG_OF) static struct at91_twi_pdata at91sam9x5_config = { .clk_max_div = 7, .clk_offset = 4, .has_unre_flag = false, .has_dma_support = true, }; static const struct of_device_id atmel_twi_dt_ids[] = { { .compatible = "atmel,at91rm9200-i2c", .data = &at91rm9200_config, } , { .compatible = "atmel,at91sam9260-i2c", .data = &at91sam9260_config, } , { .compatible = "atmel,at91sam9261-i2c", .data = &at91sam9261_config, } , { .compatible = "atmel,at91sam9g20-i2c", .data = &at91sam9g20_config, } , { .compatible = "atmel,at91sam9g10-i2c", .data = &at91sam9g10_config, }, { .compatible = "atmel,at91sam9x5-i2c", .data = &at91sam9x5_config, }, { /* sentinel */ } }; MODULE_DEVICE_TABLE(of, atmel_twi_dt_ids); #endif static bool filter(struct dma_chan *chan, void *pdata) { struct at91_twi_pdata *sl_pdata = pdata; struct at_dma_slave *sl; if (!sl_pdata) return false; sl = &sl_pdata->dma_slave; if (sl && (sl->dma_dev == chan->device->dev)) { chan->private = sl; return true; } else { return false; } } static int at91_twi_configure_dma(struct at91_twi_dev *dev, u32 phy_addr) { int ret = 0; struct at91_twi_pdata *pdata = dev->pdata; struct dma_slave_config slave_config; struct at91_twi_dma *dma = &dev->dma; dma_cap_mask_t mask; memset(&slave_config, 0, sizeof(slave_config)); slave_config.src_addr = (dma_addr_t)phy_addr + AT91_TWI_RHR; slave_config.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE; slave_config.src_maxburst = 1; slave_config.dst_addr = (dma_addr_t)phy_addr + AT91_TWI_THR; slave_config.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE; slave_config.dst_maxburst = 1; slave_config.device_fc = false; dma_cap_zero(mask); dma_cap_set(DMA_SLAVE, mask); dma->chan_tx = dma_request_slave_channel_compat(mask, filter, pdata, dev->dev, "tx"); if (!dma->chan_tx) { dev_err(dev->dev, "can't get a DMA channel for tx\n"); ret = -EBUSY; goto error; } dma->chan_rx = dma_request_slave_channel_compat(mask, filter, pdata, dev->dev, "rx"); if (!dma->chan_rx) { dev_err(dev->dev, "can't get a DMA channel for rx\n"); ret = -EBUSY; goto error; } slave_config.direction = DMA_MEM_TO_DEV; if (dmaengine_slave_config(dma->chan_tx, &slave_config)) { dev_err(dev->dev, "failed to configure tx channel\n"); ret = -EINVAL; goto error; } slave_config.direction = DMA_DEV_TO_MEM; if (dmaengine_slave_config(dma->chan_rx, &slave_config)) { dev_err(dev->dev, "failed to configure rx channel\n"); ret = -EINVAL; goto error; } sg_init_table(&dma->sg, 1); dma->buf_mapped = false; dma->xfer_in_progress = false; dev_info(dev->dev, "using %s (tx) and %s (rx) for DMA transfers\n", dma_chan_name(dma->chan_tx), dma_chan_name(dma->chan_rx)); return ret; error: dev_info(dev->dev, "can't use DMA\n"); if (dma->chan_rx) dma_release_channel(dma->chan_rx); if (dma->chan_tx) dma_release_channel(dma->chan_tx); return ret; } static struct at91_twi_pdata *at91_twi_get_driver_data( struct platform_device *pdev) { if (pdev->dev.of_node) { const struct of_device_id *match; match = of_match_node(atmel_twi_dt_ids, pdev->dev.of_node); if (!match) return NULL; return (struct at91_twi_pdata *)match->data; } return (struct at91_twi_pdata *) platform_get_device_id(pdev)->driver_data; } static int at91_twi_probe(struct platform_device *pdev) { struct at91_twi_dev *dev; struct resource *mem; int rc; u32 phy_addr; u32 bus_clk_rate; 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; phy_addr = mem->start; dev->pdata = at91_twi_get_driver_data(pdev); if (!dev->pdata) return -ENODEV; dev->base = devm_ioremap_resource(&pdev->dev, mem); if (IS_ERR(dev->base)) return PTR_ERR(dev->base); 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); if (dev->pdata->has_dma_support) { if (at91_twi_configure_dma(dev, phy_addr) == 0) dev->use_dma = true; } rc = of_property_read_u32(dev->dev->of_node, "clock-frequency", &bus_clk_rate); if (rc) bus_clk_rate = DEFAULT_TWI_CLK_HZ; at91_calc_twi_clock(dev, bus_clk_rate); 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_DEPRECATED; dev->adapter.algo = &at91_twi_algorithm; dev->adapter.dev.parent = dev->dev; dev->adapter.nr = pdev->id; dev->adapter.timeout = AT91_I2C_TIMEOUT; dev->adapter.dev.of_node = pdev->dev.of_node; 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 at91_twi_remove(struct platform_device *pdev) { struct at91_twi_dev *dev = platform_get_drvdata(pdev); i2c_del_adapter(&dev->adapter); clk_disable_unprepare(dev->clk); return 0; } #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 = at91_twi_remove, .id_table = at91_twi_devtypes, .driver = { .name = "at91_i2c", .owner = THIS_MODULE, .of_match_table = of_match_ptr(atmel_twi_dt_ids), .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");