[src/trunk]: src/sys/dev/i2c - No need to use I2C_F_POLL here.

[thorpej <thorpej%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/18d3abb2bd18
branches:  trunk
changeset: 847470:18d3abb2bd18
user:      thorpej <thorpej%NetBSD.org@localhost>
date:      Mon Dec 23 18:49:13 2019 +0000

description:
- No need to use I2C_F_POLL here.
- Use a local mutex to protect register read-modify-write cycles.

diffstat:

 sys/dev/i2c/max77620.c |  34 ++++++++++++++++++++++++++++------
 1 files changed, 28 insertions(+), 6 deletions(-)

diffs (120 lines):

diff -r a6a6a91453ea -r 18d3abb2bd18 sys/dev/i2c/max77620.c
--- a/sys/dev/i2c/max77620.c    Mon Dec 23 18:20:02 2019 +0000
+++ b/sys/dev/i2c/max77620.c    Mon Dec 23 18:49:13 2019 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: max77620.c,v 1.6 2018/06/26 06:03:57 thorpej Exp $ */
+/* $NetBSD: max77620.c,v 1.7 2019/12/23 18:49:13 thorpej Exp $ */
 
 /*-
  * Copyright (c) 2017 Jared McNeill <jmcneill%invisible.ca@localhost>
@@ -27,10 +27,11 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: max77620.c,v 1.6 2018/06/26 06:03:57 thorpej Exp $");
+__KERNEL_RCSID(0, "$NetBSD: max77620.c,v 1.7 2019/12/23 18:49:13 thorpej Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
+#include <sys/mutex.h>
 #include <sys/kernel.h>
 #include <sys/device.h>
 #include <sys/conf.h>
@@ -57,6 +58,13 @@
        i2c_tag_t       sc_i2c;
        i2c_addr_t      sc_addr;
        int             sc_phandle;
+
+       /*
+        * Locking order:
+        *
+        *      max77620 -> i2c
+        */
+       kmutex_t        sc_lock;
 };
 
 struct max77620_pin {
@@ -96,10 +104,10 @@
                aprint_error_dev(sc->sc_dev, "error writing reg %#x: %d\n", reg, error);
 }
 
-#define        I2C_READ(sc, reg)       max77620_read((sc), (reg), I2C_F_POLL)
-#define        I2C_WRITE(sc, reg, val) max77620_write((sc), (reg), (val), I2C_F_POLL)
-#define        I2C_LOCK(sc)            iic_acquire_bus((sc)->sc_i2c, I2C_F_POLL)
-#define        I2C_UNLOCK(sc)          iic_release_bus((sc)->sc_i2c, I2C_F_POLL)
+#define        I2C_READ(sc, reg)       max77620_read((sc), (reg), 0)
+#define        I2C_WRITE(sc, reg, val) max77620_write((sc), (reg), (val), 0)
+#define        I2C_LOCK(sc)            iic_acquire_bus((sc)->sc_i2c, 0)
+#define        I2C_UNLOCK(sc)          iic_release_bus((sc)->sc_i2c, 0)
 
 static int
 max77620_gpio_config(struct max77620_softc *sc, int pin, int flags)
@@ -107,6 +115,7 @@
        uint32_t gpio;
 
        KASSERT(pin >= 0 && pin < MAX_GPIO_COUNT);
+       KASSERT(mutex_owned(&sc->sc_lock));
 
        gpio = I2C_READ(sc, MAX_GPIO_REG(pin));
 
@@ -161,9 +170,11 @@
        if (pin >= MAX_GPIO_COUNT)
                return NULL;
 
+       mutex_enter(&sc->sc_lock);
        I2C_LOCK(sc);
        error = max77620_gpio_config(sc, pin, flags);
        I2C_UNLOCK(sc);
+       mutex_exit(&sc->sc_lock);
 
        if (error != 0) {
                device_printf(dev, "bad pin %d config %#x\n", pin, flags);
@@ -185,9 +196,11 @@
        struct max77620_softc * const sc = device_private(dev);
        struct max77620_pin *gpin = priv;
 
+       mutex_enter(&sc->sc_lock);
        I2C_LOCK(sc);
        max77620_gpio_config(sc, gpin->pin_num, GPIO_PIN_INPUT|GPIO_PIN_OPENDRAIN);
        I2C_UNLOCK(sc);
+       mutex_exit(&sc->sc_lock);
 
        kmem_free(gpin, sizeof(*gpin));
 }
@@ -200,6 +213,11 @@
        uint8_t gpio;
        int val;
 
+       /*
+        * Performing a register read only; no need to acquire
+        * the max77620 lock.
+        */
+
        I2C_LOCK(sc);
        gpio = I2C_READ(sc, MAX_GPIO_REG(gpin->pin_num));
        I2C_UNLOCK(sc);
@@ -227,6 +245,7 @@
        if (!raw && gpin->pin_actlo)
                val = !val;
 
+       mutex_enter(&sc->sc_lock);
        I2C_LOCK(sc);
        gpio = I2C_READ(sc, MAX_GPIO_REG(gpin->pin_num));
        gpio &= ~MAX_GPIO_OUTPUT_VAL;
@@ -238,6 +257,7 @@
 #endif
        I2C_WRITE(sc, MAX_GPIO_REG(gpin->pin_num), gpio);
        I2C_UNLOCK(sc);
+       mutex_exit(&sc->sc_lock);
 }
 
 static struct fdtbus_gpio_controller_func max77620_gpio_funcs = {
@@ -277,6 +297,8 @@
        sc->sc_addr = ia->ia_addr;
        sc->sc_phandle = ia->ia_cookie;
 
+       mutex_init(&sc->sc_lock, MUTEX_DEFAULT, IPL_NONE);
+
        aprint_naive("\n");
        aprint_normal(": MAX77620 Power Management IC\n");