i2c: pxa: implement generic i2c bus recovery (7c9ec2c5) · Commits · EulixOS / Software / Kernel

drivers/i2c/busses/i2c-pxa.c

+159 −17

Original line number	Diff line number	Diff line
		@@ -20,6 +20,7 @@
		#include <linux/delay.h>
		#include <linux/err.h>
		#include <linux/errno.h>
		#include <linux/gpio/consumer.h>
		#include <linux/i2c.h>
		#include <linux/init.h>
		#include <linux/interrupt.h>
		@@ -28,6 +29,7 @@
		#include <linux/module.h>
		#include <linux/of.h>
		#include <linux/of_device.h>
		#include <linux/pinctrl/consumer.h>
		#include <linux/platform_device.h>
		#include <linux/platform_data/i2c-pxa.h>
		#include <linux/slab.h>
		@@ -260,6 +262,11 @@ struct pxa_i2c {
		bool highmode_enter;
		u32 fm_mask;
		u32 hs_mask;

		struct i2c_bus_recovery_info recovery;
		struct pinctrl *pinctrl;
		struct pinctrl_state *pinctrl_default;
		struct pinctrl_state *pinctrl_recovery;
		};

		#define _IBMR(i2c) ((i2c)->reg_ibmr)
		@@ -559,13 +566,8 @@ static void i2c_pxa_set_slave(struct pxa_i2c *i2c, int errcode)
		#define i2c_pxa_set_slave(i2c, err) do { } while (0)
		#endif

		static void i2c_pxa_reset(struct pxa_i2c *i2c)
		static void i2c_pxa_do_reset(struct pxa_i2c *i2c)
		{
		pr_debug("Resetting I2C Controller Unit\n");

		/* abort any transfer currently under way */
		i2c_pxa_abort(i2c);

		/* reset according to 9.8 */
		writel(ICR_UR, _ICR(i2c));
		writel(I2C_ISR_INIT, _ISR(i2c));
		@@ -584,12 +586,25 @@ static void i2c_pxa_reset(struct pxa_i2c *i2c)
		#endif

		i2c_pxa_set_slave(i2c, 0);
		}

		static void i2c_pxa_enable(struct pxa_i2c *i2c)
		{
		/* enable unit */
		writel(readl(_ICR(i2c)) \| ICR_IUE, _ICR(i2c));
		udelay(100);
		}

		static void i2c_pxa_reset(struct pxa_i2c *i2c)
		{
		pr_debug("Resetting I2C Controller Unit\n");

		/* abort any transfer currently under way */
		i2c_pxa_abort(i2c);
		i2c_pxa_do_reset(i2c);
		i2c_pxa_enable(i2c);
		}


		#ifdef CONFIG_I2C_PXA_SLAVE
		/*
		@@ -1043,6 +1058,7 @@ static int i2c_pxa_do_xfer(struct pxa_i2c i2c, struct i2c_msg msg, int num)
		ret = i2c_pxa_wait_bus_not_busy(i2c);
		if (ret) {
		dev_err(&i2c->adap.dev, "i2c_pxa: timeout waiting for bus free\n");
		i2c_recover_bus(&i2c->adap);
		goto out;
		}

		@@ -1088,6 +1104,7 @@ static int i2c_pxa_do_xfer(struct pxa_i2c i2c, struct i2c_msg msg, int num)

		if (!timeout && i2c->msg_num) {
		i2c_pxa_scream_blue_murder(i2c, "timeout with active message");
		i2c_recover_bus(&i2c->adap);
		ret = I2C_RETRY;
		}

		@@ -1277,6 +1294,129 @@ static int i2c_pxa_probe_pdata(struct platform_device *pdev,
		return 0;
		}

		static void i2c_pxa_prepare_recovery(struct i2c_adapter *adap)
		{
		struct pxa_i2c *i2c = adap->algo_data;
		u32 ibmr = readl(_IBMR(i2c));

		/*
		* Program the GPIOs to reflect the current I2C bus state while
		* we transition to recovery; this avoids glitching the bus.
		*/
		gpiod_set_value(i2c->recovery.scl_gpiod, ibmr & IBMR_SCLS);
		gpiod_set_value(i2c->recovery.sda_gpiod, ibmr & IBMR_SDAS);

		WARN_ON(pinctrl_select_state(i2c->pinctrl, i2c->pinctrl_recovery));
		}

		static void i2c_pxa_unprepare_recovery(struct i2c_adapter *adap)
		{
		struct pxa_i2c *i2c = adap->algo_data;
		u32 isr;

		/*
		* The bus should now be free. Clear up the I2C controller before
		* handing control of the bus back to avoid the bus changing state.
		*/
		isr = readl(_ISR(i2c));
		if (isr & (ISR_UB \| ISR_IBB)) {
		dev_dbg(&i2c->adap.dev,
		"recovery: resetting controller, ISR=0x%08x\n", isr);
		i2c_pxa_do_reset(i2c);
		}

		WARN_ON(pinctrl_select_state(i2c->pinctrl, i2c->pinctrl_default));

		dev_dbg(&i2c->adap.dev, "recovery: IBMR 0x%08x ISR 0x%08x\n",
		readl(_IBMR(i2c)), readl(_ISR(i2c)));

		i2c_pxa_enable(i2c);
		}

		static int i2c_pxa_init_recovery(struct pxa_i2c *i2c)
		{
		struct i2c_bus_recovery_info *bri = &i2c->recovery;
		struct device *dev = i2c->adap.dev.parent;

		/*
		* When slave mode is enabled, we are not the only master on the bus.
		* Bus recovery can only be performed when we are the master, which
		* we can't be certain of. Therefore, when slave mode is enabled, do
		* not configure bus recovery.
		*/
		if (IS_ENABLED(CONFIG_I2C_PXA_SLAVE))
		return 0;

		i2c->pinctrl = devm_pinctrl_get(dev);
		if (IS_ERR(i2c->pinctrl))
		return PTR_ERR(i2c->pinctrl);

		if (!i2c->pinctrl)
		return 0;

		i2c->pinctrl_default = pinctrl_lookup_state(i2c->pinctrl,
		PINCTRL_STATE_DEFAULT);
		i2c->pinctrl_recovery = pinctrl_lookup_state(i2c->pinctrl, "recovery");

		if (IS_ERR(i2c->pinctrl_default) \|\| IS_ERR(i2c->pinctrl_recovery)) {
		dev_info(dev, "missing pinmux recovery information: %ld %ld\n",
		PTR_ERR(i2c->pinctrl_default),
		PTR_ERR(i2c->pinctrl_recovery));
		return 0;
		}

		/*
		* Claiming GPIOs can influence the pinmux state, and may glitch the
		* I2C bus. Do this carefully.
		*/
		bri->scl_gpiod = devm_gpiod_get(dev, "scl", GPIOD_OUT_HIGH_OPEN_DRAIN);
		if (bri->scl_gpiod == ERR_PTR(-EPROBE_DEFER))
		return -EPROBE_DEFER;
		if (IS_ERR(bri->scl_gpiod)) {
		dev_info(dev, "missing scl gpio recovery information: %pe\n",
		bri->scl_gpiod);
		return 0;
		}

		/*
		* We have SCL. Pull SCL low and wait a bit so that SDA glitches
		* have no effect.
		*/
		gpiod_direction_output(bri->scl_gpiod, 0);
		udelay(10);
		bri->sda_gpiod = devm_gpiod_get(dev, "sda", GPIOD_OUT_HIGH_OPEN_DRAIN);

		/* Wait a bit in case of a SDA glitch, and then release SCL. */
		udelay(10);
		gpiod_direction_output(bri->scl_gpiod, 1);

		if (bri->sda_gpiod == ERR_PTR(-EPROBE_DEFER))
		return -EPROBE_DEFER;

		if (IS_ERR(bri->sda_gpiod)) {
		dev_info(dev, "missing sda gpio recovery information: %pe\n",
		bri->sda_gpiod);
		return 0;
		}

		bri->prepare_recovery = i2c_pxa_prepare_recovery;
		bri->unprepare_recovery = i2c_pxa_unprepare_recovery;
		bri->recover_bus = i2c_generic_scl_recovery;

		i2c->adap.bus_recovery_info = bri;

		/*
		* Claiming GPIOs can change the pinmux state, which confuses the
		* pinctrl since pinctrl's idea of the current setting is unaffected
		* by the pinmux change caused by claiming the GPIO. Work around that
		* by switching pinctrl to the GPIO state here. We do it this way to
		* avoid glitching the I2C bus.
		*/
		pinctrl_select_state(i2c->pinctrl, i2c->pinctrl_recovery);

		return pinctrl_select_state(i2c->pinctrl, i2c->pinctrl_default);
		}

		static int i2c_pxa_probe(struct platform_device *dev)
		{
		struct i2c_pxa_platform_data *plat = dev_get_platdata(&dev->dev);
		@@ -1289,6 +1429,16 @@ static int i2c_pxa_probe(struct platform_device *dev)
		if (!i2c)
		return -ENOMEM;

		/* Default adapter num to device id; i2c_pxa_probe_dt can override. */
		i2c->adap.nr = dev->id;
		i2c->adap.owner = THIS_MODULE;
		i2c->adap.retries = 5;
		i2c->adap.algo_data = i2c;
		i2c->adap.dev.parent = &dev->dev;
		#ifdef CONFIG_OF
		i2c->adap.dev.of_node = dev->dev.of_node;
		#endif

		res = platform_get_resource(dev, IORESOURCE_MEM, 0);
		i2c->reg_base = devm_ioremap_resource(&dev->dev, res);
		if (IS_ERR(i2c->reg_base))
		@@ -1298,8 +1448,9 @@ static int i2c_pxa_probe(struct platform_device *dev)
		if (irq < 0)
		return irq;

		/* Default adapter num to device id; i2c_pxa_probe_dt can override. */
		i2c->adap.nr = dev->id;
		ret = i2c_pxa_init_recovery(i2c);
		if (ret)
		return ret;

		ret = i2c_pxa_probe_dt(dev, i2c, &i2c_type);
		if (ret > 0)
		@@ -1307,9 +1458,6 @@ static int i2c_pxa_probe(struct platform_device *dev)
		if (ret < 0)
		return ret;

		i2c->adap.owner = THIS_MODULE;
		i2c->adap.retries = 5;

		spin_lock_init(&i2c->lock);
		init_waitqueue_head(&i2c->wait);

		@@ -1375,12 +1523,6 @@ static int i2c_pxa_probe(struct platform_device *dev)

		i2c_pxa_reset(i2c);

		i2c->adap.algo_data = i2c;
		i2c->adap.dev.parent = &dev->dev;
		#ifdef CONFIG_OF
		i2c->adap.dev.of_node = dev->dev.of_node;
		#endif

		ret = i2c_add_numbered_adapter(&i2c->adap);
		if (ret < 0)
		goto ereqirq;