diff options
Diffstat (limited to 'drivers/i2c/busses/i2c-bcm2835.c')
| -rw-r--r-- | drivers/i2c/busses/i2c-bcm2835.c | 342 |
1 files changed, 342 insertions, 0 deletions
diff --git a/drivers/i2c/busses/i2c-bcm2835.c b/drivers/i2c/busses/i2c-bcm2835.c new file mode 100644 index 00000000000..ea4b08fc335 --- /dev/null +++ b/drivers/i2c/busses/i2c-bcm2835.c @@ -0,0 +1,342 @@ +/* + * BCM2835 master mode driver + * + * This software is licensed under the terms of the GNU General Public + * License version 2, as published by the Free Software Foundation, and + * may be copied, distributed, and modified under those terms. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ + +#include <linux/clk.h> +#include <linux/completion.h> +#include <linux/err.h> +#include <linux/i2c.h> +#include <linux/interrupt.h> +#include <linux/io.h> +#include <linux/module.h> +#include <linux/platform_device.h> +#include <linux/slab.h> + +#define BCM2835_I2C_C 0x0 +#define BCM2835_I2C_S 0x4 +#define BCM2835_I2C_DLEN 0x8 +#define BCM2835_I2C_A 0xc +#define BCM2835_I2C_FIFO 0x10 +#define BCM2835_I2C_DIV 0x14 +#define BCM2835_I2C_DEL 0x18 +#define BCM2835_I2C_CLKT 0x1c + +#define BCM2835_I2C_C_READ BIT(0) +#define BCM2835_I2C_C_CLEAR BIT(4) /* bits 4 and 5 both clear */ +#define BCM2835_I2C_C_ST BIT(7) +#define BCM2835_I2C_C_INTD BIT(8) +#define BCM2835_I2C_C_INTT BIT(9) +#define BCM2835_I2C_C_INTR BIT(10) +#define BCM2835_I2C_C_I2CEN BIT(15) + +#define BCM2835_I2C_S_TA BIT(0) +#define BCM2835_I2C_S_DONE BIT(1) +#define BCM2835_I2C_S_TXW BIT(2) +#define BCM2835_I2C_S_RXR BIT(3) +#define BCM2835_I2C_S_TXD BIT(4) +#define BCM2835_I2C_S_RXD BIT(5) +#define BCM2835_I2C_S_TXE BIT(6) +#define BCM2835_I2C_S_RXF BIT(7) +#define BCM2835_I2C_S_ERR BIT(8) +#define BCM2835_I2C_S_CLKT BIT(9) +#define BCM2835_I2C_S_LEN BIT(10) /* Fake bit for SW error reporting */ + +#define BCM2835_I2C_TIMEOUT (msecs_to_jiffies(1000)) + +struct bcm2835_i2c_dev { + struct device *dev; + void __iomem *regs; + struct clk *clk; + int irq; + struct i2c_adapter adapter; + struct completion completion; + u32 msg_err; + u8 *msg_buf; + size_t msg_buf_remaining; +}; + +static inline void bcm2835_i2c_writel(struct bcm2835_i2c_dev *i2c_dev, + u32 reg, u32 val) +{ + writel(val, i2c_dev->regs + reg); +} + +static inline u32 bcm2835_i2c_readl(struct bcm2835_i2c_dev *i2c_dev, u32 reg) +{ + return readl(i2c_dev->regs + reg); +} + +static void bcm2835_fill_txfifo(struct bcm2835_i2c_dev *i2c_dev) +{ + u32 val; + + while (i2c_dev->msg_buf_remaining) { + val = bcm2835_i2c_readl(i2c_dev, BCM2835_I2C_S); + if (!(val & BCM2835_I2C_S_TXD)) + break; + bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_FIFO, + *i2c_dev->msg_buf); + i2c_dev->msg_buf++; + i2c_dev->msg_buf_remaining--; + } +} + +static void bcm2835_drain_rxfifo(struct bcm2835_i2c_dev *i2c_dev) +{ + u32 val; + + while (i2c_dev->msg_buf_remaining) { + val = bcm2835_i2c_readl(i2c_dev, BCM2835_I2C_S); + if (!(val & BCM2835_I2C_S_RXD)) + break; + *i2c_dev->msg_buf = bcm2835_i2c_readl(i2c_dev, + BCM2835_I2C_FIFO); + i2c_dev->msg_buf++; + i2c_dev->msg_buf_remaining--; + } +} + +static irqreturn_t bcm2835_i2c_isr(int this_irq, void *data) +{ + struct bcm2835_i2c_dev *i2c_dev = data; + u32 val, err; + + val = bcm2835_i2c_readl(i2c_dev, BCM2835_I2C_S); + bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_S, val); + + err = val & (BCM2835_I2C_S_CLKT | BCM2835_I2C_S_ERR); + if (err) { + i2c_dev->msg_err = err; + complete(&i2c_dev->completion); + return IRQ_HANDLED; + } + + if (val & BCM2835_I2C_S_RXD) { + bcm2835_drain_rxfifo(i2c_dev); + if (!(val & BCM2835_I2C_S_DONE)) + return IRQ_HANDLED; + } + + if (val & BCM2835_I2C_S_DONE) { + if (i2c_dev->msg_buf_remaining) + i2c_dev->msg_err = BCM2835_I2C_S_LEN; + else + i2c_dev->msg_err = 0; + complete(&i2c_dev->completion); + return IRQ_HANDLED; + } + + if (val & BCM2835_I2C_S_TXD) { + bcm2835_fill_txfifo(i2c_dev); + return IRQ_HANDLED; + } + + return IRQ_NONE; +} + +static int bcm2835_i2c_xfer_msg(struct bcm2835_i2c_dev *i2c_dev, + struct i2c_msg *msg) +{ + u32 c; + int time_left; + + i2c_dev->msg_buf = msg->buf; + i2c_dev->msg_buf_remaining = msg->len; + INIT_COMPLETION(i2c_dev->completion); + + bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, BCM2835_I2C_C_CLEAR); + + if (msg->flags & I2C_M_RD) { + c = BCM2835_I2C_C_READ | BCM2835_I2C_C_INTR; + } else { + c = BCM2835_I2C_C_INTT; + bcm2835_fill_txfifo(i2c_dev); + } + c |= BCM2835_I2C_C_ST | BCM2835_I2C_C_INTD | BCM2835_I2C_C_I2CEN; + + bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_A, msg->addr); + bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_DLEN, msg->len); + bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, c); + + time_left = wait_for_completion_timeout(&i2c_dev->completion, + BCM2835_I2C_TIMEOUT); + bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, BCM2835_I2C_C_CLEAR); + if (!time_left) { + dev_err(i2c_dev->dev, "i2c transfer timed out\n"); + return -ETIMEDOUT; + } + + if (likely(!i2c_dev->msg_err)) + return 0; + + if ((i2c_dev->msg_err & BCM2835_I2C_S_ERR) && + (msg->flags & I2C_M_IGNORE_NAK)) + return 0; + + dev_err(i2c_dev->dev, "i2c transfer failed: %x\n", i2c_dev->msg_err); + + if (i2c_dev->msg_err & BCM2835_I2C_S_ERR) + return -EREMOTEIO; + else + return -EIO; +} + +static int bcm2835_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], + int num) +{ + struct bcm2835_i2c_dev *i2c_dev = i2c_get_adapdata(adap); + int i; + int ret = 0; + + for (i = 0; i < num; i++) { + ret = bcm2835_i2c_xfer_msg(i2c_dev, &msgs[i]); + if (ret) + break; + } + + return ret ?: i; +} + +static u32 bcm2835_i2c_func(struct i2c_adapter *adap) +{ + return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL; +} + +static const struct i2c_algorithm bcm2835_i2c_algo = { + .master_xfer = bcm2835_i2c_xfer, + .functionality = bcm2835_i2c_func, +}; + +static int bcm2835_i2c_probe(struct platform_device *pdev) +{ + struct bcm2835_i2c_dev *i2c_dev; + struct resource *mem, *requested, *irq; + u32 bus_clk_rate, divider; + int ret; + struct i2c_adapter *adap; + + i2c_dev = devm_kzalloc(&pdev->dev, sizeof(*i2c_dev), GFP_KERNEL); + if (!i2c_dev) { + dev_err(&pdev->dev, "Cannot allocate i2c_dev\n"); + return -ENOMEM; + } + platform_set_drvdata(pdev, i2c_dev); + i2c_dev->dev = &pdev->dev; + init_completion(&i2c_dev->completion); + + mem = platform_get_resource(pdev, IORESOURCE_MEM, 0); + if (!mem) { + dev_err(&pdev->dev, "No mem resource\n"); + return -ENODEV; + } + + requested = devm_request_mem_region(&pdev->dev, mem->start, + resource_size(mem), + dev_name(&pdev->dev)); + if (!requested) { + dev_err(&pdev->dev, "Could not claim register region\n"); + return -EBUSY; + } + + i2c_dev->regs = devm_ioremap(&pdev->dev, mem->start, + resource_size(mem)); + if (!i2c_dev->regs) { + dev_err(&pdev->dev, "Could not map registers\n"); + return -ENOMEM; + } + + i2c_dev->clk = devm_clk_get(&pdev->dev, NULL); + if (IS_ERR(i2c_dev->clk)) { + dev_err(&pdev->dev, "Could not get clock\n"); + return PTR_ERR(i2c_dev->clk); + } + + ret = of_property_read_u32(pdev->dev.of_node, "clock-frequency", + &bus_clk_rate); + if (ret < 0) { + dev_warn(&pdev->dev, + "Could not read clock-frequency property\n"); + bus_clk_rate = 100000; + } + + divider = DIV_ROUND_UP(clk_get_rate(i2c_dev->clk), bus_clk_rate); + /* + * Per the datasheet, the register is always interpreted as an even + * number, by rounding down. In other words, the LSB is ignored. So, + * if the LSB is set, increment the divider to avoid any issue. + */ + if (divider & 1) + divider++; + bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_DIV, divider); + + irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0); + if (!irq) { + dev_err(&pdev->dev, "No IRQ resource\n"); + return -ENODEV; + } + i2c_dev->irq = irq->start; + + ret = request_irq(i2c_dev->irq, bcm2835_i2c_isr, IRQF_SHARED, + dev_name(&pdev->dev), i2c_dev); + if (ret) { + dev_err(&pdev->dev, "Could not request IRQ\n"); + return -ENODEV; + } + + adap = &i2c_dev->adapter; + i2c_set_adapdata(adap, i2c_dev); + adap->owner = THIS_MODULE; + adap->class = I2C_CLASS_HWMON; + strlcpy(adap->name, "bcm2835 I2C adapter", sizeof(adap->name)); + adap->algo = &bcm2835_i2c_algo; + adap->dev.parent = &pdev->dev; + + bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, 0); + + ret = i2c_add_adapter(adap); + if (ret) + free_irq(i2c_dev->irq, i2c_dev); + + return ret; +} + +static int bcm2835_i2c_remove(struct platform_device *pdev) +{ + struct bcm2835_i2c_dev *i2c_dev = platform_get_drvdata(pdev); + + free_irq(i2c_dev->irq, i2c_dev); + i2c_del_adapter(&i2c_dev->adapter); + + return 0; +} + +static const struct of_device_id bcm2835_i2c_of_match[] = { + { .compatible = "brcm,bcm2835-i2c" }, + {}, +}; +MODULE_DEVICE_TABLE(of, bcm2835_i2c_of_match); + +static struct platform_driver bcm2835_i2c_driver = { + .probe = bcm2835_i2c_probe, + .remove = bcm2835_i2c_remove, + .driver = { + .name = "i2c-bcm2835", + .owner = THIS_MODULE, + .of_match_table = bcm2835_i2c_of_match, + }, +}; +module_platform_driver(bcm2835_i2c_driver); + +MODULE_AUTHOR("Stephen Warren <swarren@wwwdotorg.org>"); +MODULE_DESCRIPTION("BCM2835 I2C bus adapter"); +MODULE_LICENSE("GPL v2"); +MODULE_ALIAS("platform:i2c-bcm2835"); |