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path: root/drivers/gpio/gpio-gw-pld.c
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Diffstat (limited to 'drivers/gpio/gpio-gw-pld.c')
-rw-r--r--drivers/gpio/gpio-gw-pld.c134
1 files changed, 134 insertions, 0 deletions
diff --git a/drivers/gpio/gpio-gw-pld.c b/drivers/gpio/gpio-gw-pld.c
new file mode 100644
index 0000000000..899335da93
--- /dev/null
+++ b/drivers/gpio/gpio-gw-pld.c
@@ -0,0 +1,134 @@
+// SPDX-License-Identifier: GPL-2.0+
+//
+// Gateworks I2C PLD GPIO expander
+//
+// Copyright (C) 2019 Linus Walleij <linus.walleij@linaro.org>
+//
+// Based on code and know-how from the OpenWrt driver:
+// Copyright (C) 2009 Gateworks Corporation
+// Authors: Chris Lang, Imre Kaloz
+
+#include <linux/bits.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/gpio/driver.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+
+/**
+ * struct gw_pld - State container for Gateworks PLD
+ * @chip: GPIO chip instance
+ * @client: I2C client
+ * @out: shadow register for the output bute
+ */
+struct gw_pld {
+ struct gpio_chip chip;
+ struct i2c_client *client;
+ u8 out;
+};
+
+/*
+ * The Gateworks I2C PLD chip only expose one read and one write register.
+ * Writing a "one" bit (to match the reset state) lets that pin be used as an
+ * input. It is an open-drain model.
+ */
+static int gw_pld_input8(struct gpio_chip *gc, unsigned offset)
+{
+ struct gw_pld *gw = gpiochip_get_data(gc);
+
+ gw->out |= BIT(offset);
+ return i2c_smbus_write_byte(gw->client, gw->out);
+}
+
+static int gw_pld_get8(struct gpio_chip *gc, unsigned offset)
+{
+ struct gw_pld *gw = gpiochip_get_data(gc);
+ s32 val;
+
+ val = i2c_smbus_read_byte(gw->client);
+
+ return (val < 0) ? 0 : !!(val & BIT(offset));
+}
+
+static int gw_pld_output8(struct gpio_chip *gc, unsigned offset, int value)
+{
+ struct gw_pld *gw = gpiochip_get_data(gc);
+
+ if (value)
+ gw->out |= BIT(offset);
+ else
+ gw->out &= ~BIT(offset);
+
+ return i2c_smbus_write_byte(gw->client, gw->out);
+}
+
+static void gw_pld_set8(struct gpio_chip *gc, unsigned offset, int value)
+{
+ gw_pld_output8(gc, offset, value);
+}
+
+static int gw_pld_probe(struct i2c_client *client)
+{
+ struct device *dev = &client->dev;
+ struct gw_pld *gw;
+ int ret;
+
+ gw = devm_kzalloc(dev, sizeof(*gw), GFP_KERNEL);
+ if (!gw)
+ return -ENOMEM;
+
+ gw->chip.base = -1;
+ gw->chip.can_sleep = true;
+ gw->chip.parent = dev;
+ gw->chip.owner = THIS_MODULE;
+ gw->chip.label = dev_name(dev);
+ gw->chip.ngpio = 8;
+ gw->chip.direction_input = gw_pld_input8;
+ gw->chip.get = gw_pld_get8;
+ gw->chip.direction_output = gw_pld_output8;
+ gw->chip.set = gw_pld_set8;
+ gw->client = client;
+
+ /*
+ * The Gateworks I2C PLD chip does not properly send the acknowledge
+ * bit at all times, but we can still use the standard i2c_smbus
+ * functions by simply ignoring this bit.
+ */
+ client->flags |= I2C_M_IGNORE_NAK;
+ gw->out = 0xFF;
+
+ i2c_set_clientdata(client, gw);
+
+ ret = devm_gpiochip_add_data(dev, &gw->chip, gw);
+ if (ret)
+ return ret;
+
+ dev_info(dev, "registered Gateworks PLD GPIO device\n");
+
+ return 0;
+}
+
+static const struct i2c_device_id gw_pld_id[] = {
+ { "gw-pld", },
+ { }
+};
+MODULE_DEVICE_TABLE(i2c, gw_pld_id);
+
+static const struct of_device_id gw_pld_dt_ids[] = {
+ { .compatible = "gateworks,pld-gpio", },
+ { },
+};
+MODULE_DEVICE_TABLE(of, gw_pld_dt_ids);
+
+static struct i2c_driver gw_pld_driver = {
+ .driver = {
+ .name = "gw_pld",
+ .of_match_table = gw_pld_dt_ids,
+ },
+ .probe = gw_pld_probe,
+ .id_table = gw_pld_id,
+};
+module_i2c_driver(gw_pld_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Linus Walleij <linus.walleij@linaro.org>");