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807366af38
This patch has been backported to stable kernel 5.4 already. Remove our local patch explicitly now, as by applying the patch (or refreshing) the relevant code is actually added a second time. Refresh remaining patches as well. Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>
286 lines
8.0 KiB
Diff
286 lines
8.0 KiB
Diff
From: Russell King <rmk+kernel@armlinux.org.uk>
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Bcc: linux@mail.armlinux.org.uk
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Subject: [PATCH 7/7] i2c: pxa: implement generic i2c bus recovery
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MIME-Version: 1.0
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Content-Disposition: inline
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Content-Transfer-Encoding: 8bit
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Content-Type: text/plain; charset="utf-8"
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Implement generic GPIO-based I2C bus recovery for the PXA I2C driver.
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Reviewed-by: Andrew Lunn <andrew@lunn.ch>
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Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
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---
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drivers/i2c/busses/i2c-pxa.c | 176 +++++++++++++++++++++++++++++++----
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1 file changed, 159 insertions(+), 17 deletions(-)
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--- a/drivers/i2c/busses/i2c-pxa.c
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+++ b/drivers/i2c/busses/i2c-pxa.c
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@@ -20,6 +20,7 @@
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#include <linux/delay.h>
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#include <linux/err.h>
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#include <linux/errno.h>
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+#include <linux/gpio/consumer.h>
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#include <linux/i2c.h>
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#include <linux/i2c-pxa.h>
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#include <linux/init.h>
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@@ -29,6 +30,7 @@
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#include <linux/module.h>
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#include <linux/of.h>
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#include <linux/of_device.h>
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+#include <linux/pinctrl/consumer.h>
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#include <linux/platform_device.h>
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#include <linux/platform_data/i2c-pxa.h>
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#include <linux/slab.h>
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@@ -261,6 +263,11 @@ struct pxa_i2c {
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bool highmode_enter;
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u32 fm_mask;
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u32 hs_mask;
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+
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+ struct i2c_bus_recovery_info recovery;
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+ struct pinctrl *pinctrl;
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+ struct pinctrl_state *pinctrl_default;
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+ struct pinctrl_state *pinctrl_recovery;
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};
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#define _IBMR(i2c) ((i2c)->reg_ibmr)
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@@ -560,13 +567,8 @@ static void i2c_pxa_set_slave(struct pxa
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#define i2c_pxa_set_slave(i2c, err) do { } while (0)
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#endif
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-static void i2c_pxa_reset(struct pxa_i2c *i2c)
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+static void i2c_pxa_do_reset(struct pxa_i2c *i2c)
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{
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- pr_debug("Resetting I2C Controller Unit\n");
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-
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- /* abort any transfer currently under way */
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- i2c_pxa_abort(i2c);
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-
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/* reset according to 9.8 */
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writel(ICR_UR, _ICR(i2c));
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writel(I2C_ISR_INIT, _ISR(i2c));
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@@ -585,12 +587,25 @@ static void i2c_pxa_reset(struct pxa_i2c
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#endif
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i2c_pxa_set_slave(i2c, 0);
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+}
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+static void i2c_pxa_enable(struct pxa_i2c *i2c)
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+{
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/* enable unit */
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writel(readl(_ICR(i2c)) | ICR_IUE, _ICR(i2c));
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udelay(100);
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}
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+static void i2c_pxa_reset(struct pxa_i2c *i2c)
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+{
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+ pr_debug("Resetting I2C Controller Unit\n");
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+
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+ /* abort any transfer currently under way */
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+ i2c_pxa_abort(i2c);
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+ i2c_pxa_do_reset(i2c);
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+ i2c_pxa_enable(i2c);
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+}
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+
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#ifdef CONFIG_I2C_PXA_SLAVE
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/*
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@@ -1002,6 +1017,7 @@ static int i2c_pxa_do_xfer(struct pxa_i2
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ret = i2c_pxa_wait_bus_not_busy(i2c);
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if (ret) {
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dev_err(&i2c->adap.dev, "i2c_pxa: timeout waiting for bus free\n");
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+ i2c_recover_bus(&i2c->adap);
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goto out;
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}
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@@ -1047,6 +1063,7 @@ static int i2c_pxa_do_xfer(struct pxa_i2
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if (!timeout && i2c->msg_num) {
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i2c_pxa_scream_blue_murder(i2c, "timeout with active message");
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+ i2c_recover_bus(&i2c->adap);
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ret = I2C_RETRY;
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}
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@@ -1228,6 +1245,129 @@ static int i2c_pxa_probe_pdata(struct pl
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return 0;
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}
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+static void i2c_pxa_prepare_recovery(struct i2c_adapter *adap)
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+{
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+ struct pxa_i2c *i2c = adap->algo_data;
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+ u32 ibmr = readl(_IBMR(i2c));
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+
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+ /*
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+ * Program the GPIOs to reflect the current I2C bus state while
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+ * we transition to recovery; this avoids glitching the bus.
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+ */
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+ gpiod_set_value(i2c->recovery.scl_gpiod, ibmr & IBMR_SCLS);
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+ gpiod_set_value(i2c->recovery.sda_gpiod, ibmr & IBMR_SDAS);
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+
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+ WARN_ON(pinctrl_select_state(i2c->pinctrl, i2c->pinctrl_recovery));
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+}
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+
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+static void i2c_pxa_unprepare_recovery(struct i2c_adapter *adap)
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+{
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+ struct pxa_i2c *i2c = adap->algo_data;
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+ u32 isr;
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+
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+ /*
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+ * The bus should now be free. Clear up the I2C controller before
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+ * handing control of the bus back to avoid the bus changing state.
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+ */
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+ isr = readl(_ISR(i2c));
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+ if (isr & (ISR_UB | ISR_IBB)) {
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+ dev_dbg(&i2c->adap.dev,
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+ "recovery: resetting controller, ISR=0x%08x\n", isr);
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+ i2c_pxa_do_reset(i2c);
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+ }
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+
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+ WARN_ON(pinctrl_select_state(i2c->pinctrl, i2c->pinctrl_default));
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+
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+ dev_dbg(&i2c->adap.dev, "recovery: IBMR 0x%08x ISR 0x%08x\n",
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+ readl(_IBMR(i2c)), readl(_ISR(i2c)));
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+
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+ i2c_pxa_enable(i2c);
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+}
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+
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+static int i2c_pxa_init_recovery(struct pxa_i2c *i2c)
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+{
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+ struct i2c_bus_recovery_info *bri = &i2c->recovery;
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+ struct device *dev = i2c->adap.dev.parent;
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+
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+ /*
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+ * When slave mode is enabled, we are not the only master on the bus.
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+ * Bus recovery can only be performed when we are the master, which
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+ * we can't be certain of. Therefore, when slave mode is enabled, do
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+ * not configure bus recovery.
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+ */
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+ if (IS_ENABLED(CONFIG_I2C_PXA_SLAVE))
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+ return 0;
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+
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+ i2c->pinctrl = devm_pinctrl_get(dev);
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+ if (IS_ERR(i2c->pinctrl))
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+ return PTR_ERR(i2c->pinctrl);
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+
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+ if (!i2c->pinctrl)
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+ return 0;
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+
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+ i2c->pinctrl_default = pinctrl_lookup_state(i2c->pinctrl,
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+ PINCTRL_STATE_DEFAULT);
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+ i2c->pinctrl_recovery = pinctrl_lookup_state(i2c->pinctrl, "recovery");
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+
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+ if (IS_ERR(i2c->pinctrl_default) || IS_ERR(i2c->pinctrl_recovery)) {
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+ dev_info(dev, "missing pinmux recovery information: %ld %ld\n",
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+ PTR_ERR(i2c->pinctrl_default),
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+ PTR_ERR(i2c->pinctrl_recovery));
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+ return 0;
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+ }
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+
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+ /*
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+ * Claiming GPIOs can influence the pinmux state, and may glitch the
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+ * I2C bus. Do this carefully.
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+ */
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+ bri->scl_gpiod = devm_gpiod_get(dev, "scl", GPIOD_OUT_HIGH_OPEN_DRAIN);
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+ if (bri->scl_gpiod == ERR_PTR(-EPROBE_DEFER))
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+ return -EPROBE_DEFER;
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+ if (IS_ERR(bri->scl_gpiod)) {
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+ dev_info(dev, "missing scl gpio recovery information: %pe\n",
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+ bri->scl_gpiod);
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+ return 0;
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+ }
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+
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+ /*
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+ * We have SCL. Pull SCL low and wait a bit so that SDA glitches
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+ * have no effect.
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+ */
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+ gpiod_direction_output(bri->scl_gpiod, 0);
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+ udelay(10);
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+ bri->sda_gpiod = devm_gpiod_get(dev, "sda", GPIOD_OUT_HIGH_OPEN_DRAIN);
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+
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+ /* Wait a bit in case of a SDA glitch, and then release SCL. */
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+ udelay(10);
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+ gpiod_direction_output(bri->scl_gpiod, 1);
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+
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+ if (bri->sda_gpiod == ERR_PTR(-EPROBE_DEFER))
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+ return -EPROBE_DEFER;
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+
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+ if (IS_ERR(bri->sda_gpiod)) {
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+ dev_info(dev, "missing sda gpio recovery information: %pe\n",
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+ bri->sda_gpiod);
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+ return 0;
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+ }
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+
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+ bri->prepare_recovery = i2c_pxa_prepare_recovery;
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+ bri->unprepare_recovery = i2c_pxa_unprepare_recovery;
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+ bri->recover_bus = i2c_generic_scl_recovery;
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+
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+ i2c->adap.bus_recovery_info = bri;
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+
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+ /*
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+ * Claiming GPIOs can change the pinmux state, which confuses the
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+ * pinctrl since pinctrl's idea of the current setting is unaffected
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+ * by the pinmux change caused by claiming the GPIO. Work around that
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+ * by switching pinctrl to the GPIO state here. We do it this way to
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+ * avoid glitching the I2C bus.
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+ */
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+ pinctrl_select_state(i2c->pinctrl, i2c->pinctrl_recovery);
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+
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+ return pinctrl_select_state(i2c->pinctrl, i2c->pinctrl_default);
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+}
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+
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static int i2c_pxa_probe(struct platform_device *dev)
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{
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struct i2c_pxa_platform_data *plat = dev_get_platdata(&dev->dev);
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@@ -1240,6 +1380,16 @@ static int i2c_pxa_probe(struct platform
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if (!i2c)
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return -ENOMEM;
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+ /* Default adapter num to device id; i2c_pxa_probe_dt can override. */
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+ i2c->adap.nr = dev->id;
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+ i2c->adap.owner = THIS_MODULE;
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+ i2c->adap.retries = 5;
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+ i2c->adap.algo_data = i2c;
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+ i2c->adap.dev.parent = &dev->dev;
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+#ifdef CONFIG_OF
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+ i2c->adap.dev.of_node = dev->dev.of_node;
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+#endif
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+
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res = platform_get_resource(dev, IORESOURCE_MEM, 0);
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i2c->reg_base = devm_ioremap_resource(&dev->dev, res);
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if (IS_ERR(i2c->reg_base))
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@@ -1251,8 +1401,9 @@ static int i2c_pxa_probe(struct platform
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return irq;
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}
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- /* Default adapter num to device id; i2c_pxa_probe_dt can override. */
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- i2c->adap.nr = dev->id;
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+ ret = i2c_pxa_init_recovery(i2c);
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+ if (ret)
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+ return ret;
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ret = i2c_pxa_probe_dt(dev, i2c, &i2c_type);
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if (ret > 0)
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@@ -1260,9 +1411,6 @@ static int i2c_pxa_probe(struct platform
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if (ret < 0)
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return ret;
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- i2c->adap.owner = THIS_MODULE;
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- i2c->adap.retries = 5;
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-
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spin_lock_init(&i2c->lock);
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init_waitqueue_head(&i2c->wait);
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@@ -1332,12 +1480,6 @@ static int i2c_pxa_probe(struct platform
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i2c_pxa_reset(i2c);
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- i2c->adap.algo_data = i2c;
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- i2c->adap.dev.parent = &dev->dev;
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-#ifdef CONFIG_OF
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- i2c->adap.dev.of_node = dev->dev.of_node;
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-#endif
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-
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ret = i2c_add_numbered_adapter(&i2c->adap);
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if (ret < 0)
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goto ereqirq;
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