diff options
Diffstat (limited to 'drivers/i2c/busses/i2c-efm32.c')
| -rw-r--r-- | drivers/i2c/busses/i2c-efm32.c | 481 |
1 files changed, 481 insertions, 0 deletions
diff --git a/drivers/i2c/busses/i2c-efm32.c b/drivers/i2c/busses/i2c-efm32.c new file mode 100644 index 00000000000..777ed409a24 --- /dev/null +++ b/drivers/i2c/busses/i2c-efm32.c @@ -0,0 +1,481 @@ +/* + * Copyright (C) 2014 Uwe Kleine-Koenig for Pengutronix + * + * 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/module.h> +#include <linux/platform_device.h> +#include <linux/i2c.h> +#include <linux/io.h> +#include <linux/interrupt.h> +#include <linux/err.h> +#include <linux/clk.h> + +#define DRIVER_NAME "efm32-i2c" + +#define MASK_VAL(mask, val) ((val << __ffs(mask)) & mask) + +#define REG_CTRL 0x00 +#define REG_CTRL_EN 0x00001 +#define REG_CTRL_SLAVE 0x00002 +#define REG_CTRL_AUTOACK 0x00004 +#define REG_CTRL_AUTOSE 0x00008 +#define REG_CTRL_AUTOSN 0x00010 +#define REG_CTRL_ARBDIS 0x00020 +#define REG_CTRL_GCAMEN 0x00040 +#define REG_CTRL_CLHR__MASK 0x00300 +#define REG_CTRL_BITO__MASK 0x03000 +#define REG_CTRL_BITO_OFF 0x00000 +#define REG_CTRL_BITO_40PCC 0x01000 +#define REG_CTRL_BITO_80PCC 0x02000 +#define REG_CTRL_BITO_160PCC 0x03000 +#define REG_CTRL_GIBITO 0x08000 +#define REG_CTRL_CLTO__MASK 0x70000 +#define REG_CTRL_CLTO_OFF 0x00000 + +#define REG_CMD 0x04 +#define REG_CMD_START 0x00001 +#define REG_CMD_STOP 0x00002 +#define REG_CMD_ACK 0x00004 +#define REG_CMD_NACK 0x00008 +#define REG_CMD_CONT 0x00010 +#define REG_CMD_ABORT 0x00020 +#define REG_CMD_CLEARTX 0x00040 +#define REG_CMD_CLEARPC 0x00080 + +#define REG_STATE 0x08 +#define REG_STATE_BUSY 0x00001 +#define REG_STATE_MASTER 0x00002 +#define REG_STATE_TRANSMITTER 0x00004 +#define REG_STATE_NACKED 0x00008 +#define REG_STATE_BUSHOLD 0x00010 +#define REG_STATE_STATE__MASK 0x000e0 +#define REG_STATE_STATE_IDLE 0x00000 +#define REG_STATE_STATE_WAIT 0x00020 +#define REG_STATE_STATE_START 0x00040 +#define REG_STATE_STATE_ADDR 0x00060 +#define REG_STATE_STATE_ADDRACK 0x00080 +#define REG_STATE_STATE_DATA 0x000a0 +#define REG_STATE_STATE_DATAACK 0x000c0 + +#define REG_STATUS 0x0c +#define REG_STATUS_PSTART 0x00001 +#define REG_STATUS_PSTOP 0x00002 +#define REG_STATUS_PACK 0x00004 +#define REG_STATUS_PNACK 0x00008 +#define REG_STATUS_PCONT 0x00010 +#define REG_STATUS_PABORT 0x00020 +#define REG_STATUS_TXC 0x00040 +#define REG_STATUS_TXBL 0x00080 +#define REG_STATUS_RXDATAV 0x00100 + +#define REG_CLKDIV 0x10 +#define REG_CLKDIV_DIV__MASK 0x001ff +#define REG_CLKDIV_DIV(div) MASK_VAL(REG_CLKDIV_DIV__MASK, (div)) + +#define REG_SADDR 0x14 +#define REG_SADDRMASK 0x18 +#define REG_RXDATA 0x1c +#define REG_RXDATAP 0x20 +#define REG_TXDATA 0x24 +#define REG_IF 0x28 +#define REG_IF_START 0x00001 +#define REG_IF_RSTART 0x00002 +#define REG_IF_ADDR 0x00004 +#define REG_IF_TXC 0x00008 +#define REG_IF_TXBL 0x00010 +#define REG_IF_RXDATAV 0x00020 +#define REG_IF_ACK 0x00040 +#define REG_IF_NACK 0x00080 +#define REG_IF_MSTOP 0x00100 +#define REG_IF_ARBLOST 0x00200 +#define REG_IF_BUSERR 0x00400 +#define REG_IF_BUSHOLD 0x00800 +#define REG_IF_TXOF 0x01000 +#define REG_IF_RXUF 0x02000 +#define REG_IF_BITO 0x04000 +#define REG_IF_CLTO 0x08000 +#define REG_IF_SSTOP 0x10000 + +#define REG_IFS 0x2c +#define REG_IFC 0x30 +#define REG_IFC__MASK 0x1ffcf + +#define REG_IEN 0x34 + +#define REG_ROUTE 0x38 +#define REG_ROUTE_SDAPEN 0x00001 +#define REG_ROUTE_SCLPEN 0x00002 +#define REG_ROUTE_LOCATION__MASK 0x00700 +#define REG_ROUTE_LOCATION(n) MASK_VAL(REG_ROUTE_LOCATION__MASK, (n)) + +struct efm32_i2c_ddata { + struct i2c_adapter adapter; + + struct clk *clk; + void __iomem *base; + unsigned int irq; + u8 location; + unsigned long frequency; + + /* transfer data */ + struct completion done; + struct i2c_msg *msgs; + size_t num_msgs; + size_t current_word, current_msg; + int retval; +}; + +static u32 efm32_i2c_read32(struct efm32_i2c_ddata *ddata, unsigned offset) +{ + return readl(ddata->base + offset); +} + +static void efm32_i2c_write32(struct efm32_i2c_ddata *ddata, + unsigned offset, u32 value) +{ + writel(value, ddata->base + offset); +} + +static void efm32_i2c_send_next_msg(struct efm32_i2c_ddata *ddata) +{ + struct i2c_msg *cur_msg = &ddata->msgs[ddata->current_msg]; + + efm32_i2c_write32(ddata, REG_CMD, REG_CMD_START); + efm32_i2c_write32(ddata, REG_TXDATA, cur_msg->addr << 1 | + (cur_msg->flags & I2C_M_RD ? 1 : 0)); +} + +static void efm32_i2c_send_next_byte(struct efm32_i2c_ddata *ddata) +{ + struct i2c_msg *cur_msg = &ddata->msgs[ddata->current_msg]; + + if (ddata->current_word >= cur_msg->len) { + /* cur_msg completely transferred */ + ddata->current_word = 0; + ddata->current_msg += 1; + + if (ddata->current_msg >= ddata->num_msgs) { + efm32_i2c_write32(ddata, REG_CMD, REG_CMD_STOP); + complete(&ddata->done); + } else { + efm32_i2c_send_next_msg(ddata); + } + } else { + efm32_i2c_write32(ddata, REG_TXDATA, + cur_msg->buf[ddata->current_word++]); + } +} + +static void efm32_i2c_recv_next_byte(struct efm32_i2c_ddata *ddata) +{ + struct i2c_msg *cur_msg = &ddata->msgs[ddata->current_msg]; + + cur_msg->buf[ddata->current_word] = efm32_i2c_read32(ddata, REG_RXDATA); + ddata->current_word += 1; + if (ddata->current_word >= cur_msg->len) { + /* cur_msg completely transferred */ + ddata->current_word = 0; + ddata->current_msg += 1; + + efm32_i2c_write32(ddata, REG_CMD, REG_CMD_NACK); + + if (ddata->current_msg >= ddata->num_msgs) { + efm32_i2c_write32(ddata, REG_CMD, REG_CMD_STOP); + complete(&ddata->done); + } else { + efm32_i2c_send_next_msg(ddata); + } + } else { + efm32_i2c_write32(ddata, REG_CMD, REG_CMD_ACK); + } +} + +static irqreturn_t efm32_i2c_irq(int irq, void *dev_id) +{ + struct efm32_i2c_ddata *ddata = dev_id; + struct i2c_msg *cur_msg = &ddata->msgs[ddata->current_msg]; + u32 irqflag = efm32_i2c_read32(ddata, REG_IF); + u32 state = efm32_i2c_read32(ddata, REG_STATE); + + efm32_i2c_write32(ddata, REG_IFC, irqflag & REG_IFC__MASK); + + switch (state & REG_STATE_STATE__MASK) { + case REG_STATE_STATE_IDLE: + /* arbitration lost? */ + ddata->retval = -EAGAIN; + complete(&ddata->done); + break; + case REG_STATE_STATE_WAIT: + /* + * huh, this shouldn't happen. + * Reset hardware state and get out + */ + ddata->retval = -EIO; + efm32_i2c_write32(ddata, REG_CMD, + REG_CMD_STOP | REG_CMD_ABORT | + REG_CMD_CLEARTX | REG_CMD_CLEARPC); + complete(&ddata->done); + break; + case REG_STATE_STATE_START: + /* "caller" is expected to send an address */ + break; + case REG_STATE_STATE_ADDR: + /* wait for Ack or NAck of slave */ + break; + case REG_STATE_STATE_ADDRACK: + if (state & REG_STATE_NACKED) { + efm32_i2c_write32(ddata, REG_CMD, REG_CMD_STOP); + ddata->retval = -ENXIO; + complete(&ddata->done); + } else if (cur_msg->flags & I2C_M_RD) { + /* wait for slave to send first data byte */ + } else { + efm32_i2c_send_next_byte(ddata); + } + break; + case REG_STATE_STATE_DATA: + if (cur_msg->flags & I2C_M_RD) { + efm32_i2c_recv_next_byte(ddata); + } else { + /* wait for Ack or Nack of slave */ + } + break; + case REG_STATE_STATE_DATAACK: + if (state & REG_STATE_NACKED) { + efm32_i2c_write32(ddata, REG_CMD, REG_CMD_STOP); + complete(&ddata->done); + } else { + efm32_i2c_send_next_byte(ddata); + } + } + + return IRQ_HANDLED; +} + +static int efm32_i2c_master_xfer(struct i2c_adapter *adap, + struct i2c_msg *msgs, int num) +{ + struct efm32_i2c_ddata *ddata = i2c_get_adapdata(adap); + int ret; + + if (ddata->msgs) + return -EBUSY; + + ddata->msgs = msgs; + ddata->num_msgs = num; + ddata->current_word = 0; + ddata->current_msg = 0; + ddata->retval = -EIO; + + reinit_completion(&ddata->done); + + dev_dbg(&ddata->adapter.dev, "state: %08x, status: %08x\n", + efm32_i2c_read32(ddata, REG_STATE), + efm32_i2c_read32(ddata, REG_STATUS)); + + efm32_i2c_send_next_msg(ddata); + + wait_for_completion(&ddata->done); + + if (ddata->current_msg >= ddata->num_msgs) + ret = ddata->num_msgs; + else + ret = ddata->retval; + + return ret; +} + +static u32 efm32_i2c_functionality(struct i2c_adapter *adap) +{ + return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL; +} + +static const struct i2c_algorithm efm32_i2c_algo = { + .master_xfer = efm32_i2c_master_xfer, + .functionality = efm32_i2c_functionality, +}; + +static u32 efm32_i2c_get_configured_location(struct efm32_i2c_ddata *ddata) +{ + u32 reg = efm32_i2c_read32(ddata, REG_ROUTE); + + return (reg & REG_ROUTE_LOCATION__MASK) >> + __ffs(REG_ROUTE_LOCATION__MASK); +} + +static int efm32_i2c_probe(struct platform_device *pdev) +{ + struct efm32_i2c_ddata *ddata; + struct resource *res; + unsigned long rate; + struct device_node *np = pdev->dev.of_node; + u32 location, frequency; + int ret; + u32 clkdiv; + + if (!np) + return -EINVAL; + + ddata = devm_kzalloc(&pdev->dev, sizeof(*ddata), GFP_KERNEL); + if (!ddata) { + dev_dbg(&pdev->dev, "failed to allocate private data\n"); + return -ENOMEM; + } + platform_set_drvdata(pdev, ddata); + + init_completion(&ddata->done); + strlcpy(ddata->adapter.name, pdev->name, sizeof(ddata->adapter.name)); + ddata->adapter.owner = THIS_MODULE; + ddata->adapter.algo = &efm32_i2c_algo; + ddata->adapter.dev.parent = &pdev->dev; + ddata->adapter.dev.of_node = pdev->dev.of_node; + i2c_set_adapdata(&ddata->adapter, ddata); + + ddata->clk = devm_clk_get(&pdev->dev, NULL); + if (IS_ERR(ddata->clk)) { + ret = PTR_ERR(ddata->clk); + dev_err(&pdev->dev, "failed to get clock: %d\n", ret); + return ret; + } + + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + if (!res) { + dev_err(&pdev->dev, "failed to determine base address\n"); + return -ENODEV; + } + + if (resource_size(res) < 0x42) { + dev_err(&pdev->dev, "memory resource too small\n"); + return -EINVAL; + } + + ddata->base = devm_ioremap_resource(&pdev->dev, res); + if (IS_ERR(ddata->base)) + return PTR_ERR(ddata->base); + + ret = platform_get_irq(pdev, 0); + if (ret <= 0) { + dev_err(&pdev->dev, "failed to get irq (%d)\n", ret); + if (!ret) + ret = -EINVAL; + return ret; + } + + ddata->irq = ret; + + ret = clk_prepare_enable(ddata->clk); + if (ret < 0) { + dev_err(&pdev->dev, "failed to enable clock (%d)\n", ret); + return ret; + } + + ret = of_property_read_u32(np, "efm32,location", &location); + if (!ret) { + dev_dbg(&pdev->dev, "using location %u\n", location); + } else { + /* default to location configured in hardware */ + location = efm32_i2c_get_configured_location(ddata); + + dev_info(&pdev->dev, "fall back to location %u\n", location); + } + + ddata->location = location; + + ret = of_property_read_u32(np, "clock-frequency", &frequency); + if (!ret) { + dev_dbg(&pdev->dev, "using frequency %u\n", frequency); + } else { + frequency = 100000; + dev_info(&pdev->dev, "defaulting to 100 kHz\n"); + } + ddata->frequency = frequency; + + rate = clk_get_rate(ddata->clk); + if (!rate) { + dev_err(&pdev->dev, "there is no input clock available\n"); + ret = -EINVAL; + goto err_disable_clk; + } + clkdiv = DIV_ROUND_UP(rate, 8 * ddata->frequency) - 1; + if (clkdiv >= 0x200) { + dev_err(&pdev->dev, + "input clock too fast (%lu) to divide down to bus freq (%lu)", + rate, ddata->frequency); + ret = -EINVAL; + goto err_disable_clk; + } + + dev_dbg(&pdev->dev, "input clock = %lu, bus freq = %lu, clkdiv = %lu\n", + rate, ddata->frequency, (unsigned long)clkdiv); + efm32_i2c_write32(ddata, REG_CLKDIV, REG_CLKDIV_DIV(clkdiv)); + + efm32_i2c_write32(ddata, REG_ROUTE, REG_ROUTE_SDAPEN | + REG_ROUTE_SCLPEN | + REG_ROUTE_LOCATION(ddata->location)); + + efm32_i2c_write32(ddata, REG_CTRL, REG_CTRL_EN | + REG_CTRL_BITO_160PCC | 0 * REG_CTRL_GIBITO); + + efm32_i2c_write32(ddata, REG_IFC, REG_IFC__MASK); + efm32_i2c_write32(ddata, REG_IEN, REG_IF_TXC | REG_IF_ACK | REG_IF_NACK + | REG_IF_ARBLOST | REG_IF_BUSERR | REG_IF_RXDATAV); + + /* to make bus idle */ + efm32_i2c_write32(ddata, REG_CMD, REG_CMD_ABORT); + + ret = request_irq(ddata->irq, efm32_i2c_irq, 0, DRIVER_NAME, ddata); + if (ret < 0) { + dev_err(&pdev->dev, "failed to request irq (%d)\n", ret); + return ret; + } + + ret = i2c_add_adapter(&ddata->adapter); + if (ret) { + dev_err(&pdev->dev, "failed to add i2c adapter (%d)\n", ret); + free_irq(ddata->irq, ddata); + +err_disable_clk: + clk_disable_unprepare(ddata->clk); + } + return ret; +} + +static int efm32_i2c_remove(struct platform_device *pdev) +{ + struct efm32_i2c_ddata *ddata = platform_get_drvdata(pdev); + + i2c_del_adapter(&ddata->adapter); + free_irq(ddata->irq, ddata); + clk_disable_unprepare(ddata->clk); + + return 0; +} + +static const struct of_device_id efm32_i2c_dt_ids[] = { + { + .compatible = "energymicro,efm32-i2c", + }, { + /* sentinel */ + } +}; +MODULE_DEVICE_TABLE(of, efm32_i2c_dt_ids); + +static struct platform_driver efm32_i2c_driver = { + .probe = efm32_i2c_probe, + .remove = efm32_i2c_remove, + + .driver = { + .name = DRIVER_NAME, + .owner = THIS_MODULE, + .of_match_table = efm32_i2c_dt_ids, + }, +}; +module_platform_driver(efm32_i2c_driver); + +MODULE_AUTHOR("Uwe Kleine-Koenig <u.kleine-koenig@pengutronix.de>"); +MODULE_DESCRIPTION("EFM32 i2c driver"); +MODULE_LICENSE("GPL v2"); +MODULE_ALIAS("platform:" DRIVER_NAME); |