// SPDX-License-Identifier: GPL-2.0 /* * BCM2835 I2C controller driver */ #include <linux/clk.h> #include <linux/clkdev.h> #include <linux/clk-provider.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/of.h> #include <linux/platform_device.h> #include <linux/slab.h> #define BCM2835_I2C_C … #define BCM2835_I2C_S … #define BCM2835_I2C_DLEN … #define BCM2835_I2C_A … #define BCM2835_I2C_FIFO … #define BCM2835_I2C_DIV … #define BCM2835_I2C_DEL … /* * 16-bit field for the number of SCL cycles to wait after rising SCL * before deciding the target is not responding. 0 disables the * timeout detection. */ #define BCM2835_I2C_CLKT … #define BCM2835_I2C_C_READ … #define BCM2835_I2C_C_CLEAR … #define BCM2835_I2C_C_ST … #define BCM2835_I2C_C_INTD … #define BCM2835_I2C_C_INTT … #define BCM2835_I2C_C_INTR … #define BCM2835_I2C_C_I2CEN … #define BCM2835_I2C_S_TA … #define BCM2835_I2C_S_DONE … #define BCM2835_I2C_S_TXW … #define BCM2835_I2C_S_RXR … #define BCM2835_I2C_S_TXD … #define BCM2835_I2C_S_RXD … #define BCM2835_I2C_S_TXE … #define BCM2835_I2C_S_RXF … #define BCM2835_I2C_S_ERR … #define BCM2835_I2C_S_CLKT … #define BCM2835_I2C_S_LEN … #define BCM2835_I2C_FEDL_SHIFT … #define BCM2835_I2C_REDL_SHIFT … #define BCM2835_I2C_CDIV_MIN … #define BCM2835_I2C_CDIV_MAX … struct bcm2835_i2c_dev { … }; static inline void bcm2835_i2c_writel(struct bcm2835_i2c_dev *i2c_dev, u32 reg, u32 val) { … } static inline u32 bcm2835_i2c_readl(struct bcm2835_i2c_dev *i2c_dev, u32 reg) { … } #define to_clk_bcm2835_i2c(_hw) … struct clk_bcm2835_i2c { … }; static int clk_bcm2835_i2c_calc_divider(unsigned long rate, unsigned long parent_rate) { … } static int clk_bcm2835_i2c_set_rate(struct clk_hw *hw, unsigned long rate, unsigned long parent_rate) { … } static long clk_bcm2835_i2c_round_rate(struct clk_hw *hw, unsigned long rate, unsigned long *parent_rate) { … } static unsigned long clk_bcm2835_i2c_recalc_rate(struct clk_hw *hw, unsigned long parent_rate) { … } static const struct clk_ops clk_bcm2835_i2c_ops = …; static struct clk *bcm2835_i2c_register_div(struct device *dev, struct clk *mclk, struct bcm2835_i2c_dev *i2c_dev) { … } static void bcm2835_fill_txfifo(struct bcm2835_i2c_dev *i2c_dev) { … } static void bcm2835_drain_rxfifo(struct bcm2835_i2c_dev *i2c_dev) { … } /* * Repeated Start Condition (Sr) * The BCM2835 ARM Peripherals datasheet mentions a way to trigger a Sr when it * talks about reading from a target with 10 bit address. This is achieved by * issuing a write, poll the I2CS.TA flag and wait for it to be set, and then * issue a read. * A comment in https://github.com/raspberrypi/linux/issues/254 shows how the * firmware actually does it using polling and says that it's a workaround for * a problem in the state machine. * It turns out that it is possible to use the TXW interrupt to know when the * transfer is active, provided the FIFO has not been prefilled. */ static void bcm2835_i2c_start_transfer(struct bcm2835_i2c_dev *i2c_dev) { … } static void bcm2835_i2c_finish_transfer(struct bcm2835_i2c_dev *i2c_dev) { … } /* * Note about I2C_C_CLEAR on error: * The I2C_C_CLEAR on errors will take some time to resolve -- if you were in * non-idle state and I2C_C_READ, it sets an abort_rx flag and runs through * the state machine to send a NACK and a STOP. Since we're setting CLEAR * without I2CEN, that NACK will be hanging around queued up for next time * we start the engine. */ static irqreturn_t bcm2835_i2c_isr(int this_irq, void *data) { … } static int bcm2835_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num) { … } static u32 bcm2835_i2c_func(struct i2c_adapter *adap) { … } static const struct i2c_algorithm bcm2835_i2c_algo = …; /* * The BCM2835 was reported to have problems with clock stretching: * https://www.advamation.com/knowhow/raspberrypi/rpi-i2c-bug.html * https://www.raspberrypi.org/forums/viewtopic.php?p=146272 */ static const struct i2c_adapter_quirks bcm2835_i2c_quirks = …; static int bcm2835_i2c_probe(struct platform_device *pdev) { … } static void bcm2835_i2c_remove(struct platform_device *pdev) { … } static const struct of_device_id bcm2835_i2c_of_match[] = …; MODULE_DEVICE_TABLE(of, bcm2835_i2c_of_match); static struct platform_driver bcm2835_i2c_driver = …; module_platform_driver(…) …; MODULE_AUTHOR(…) …; MODULE_DESCRIPTION(…) …; MODULE_LICENSE(…) …; MODULE_ALIAS(…) …;
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