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@@ -0,0 +1,384 @@
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+/*
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+ * Copyright 2007-2008 Extreme Engineering Solutions, Inc.
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+ *
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+ * Author: Nate Case <ncase@xes-inc.com>
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+ *
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+ * This file is subject to the terms and conditions of version 2 of
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+ * the GNU General Public License. See the file COPYING in the main
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+ * directory of this archive for more details.
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+ *
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+ * LED driver for various PCA955x I2C LED drivers
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+ *
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+ * Supported devices:
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+ *
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+ * Device Description 7-bit slave address
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+ * ------ ----------- -------------------
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+ * PCA9550 2-bit driver 0x60 .. 0x61
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+ * PCA9551 8-bit driver 0x60 .. 0x67
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+ * PCA9552 16-bit driver 0x60 .. 0x67
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+ * PCA9553/01 4-bit driver 0x62
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+ * PCA9553/02 4-bit driver 0x63
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+ *
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+ * Philips PCA955x LED driver chips follow a register map as shown below:
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+ *
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+ * Control Register Description
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+ * ---------------- -----------
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+ * 0x0 Input register 0
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+ * ..
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+ * NUM_INPUT_REGS - 1 Last Input register X
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+ *
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+ * NUM_INPUT_REGS Frequency prescaler 0
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+ * NUM_INPUT_REGS + 1 PWM register 0
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+ * NUM_INPUT_REGS + 2 Frequency prescaler 1
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+ * NUM_INPUT_REGS + 3 PWM register 1
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+ *
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+ * NUM_INPUT_REGS + 4 LED selector 0
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+ * NUM_INPUT_REGS + 4
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+ * + NUM_LED_REGS - 1 Last LED selector
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+ *
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+ * where NUM_INPUT_REGS and NUM_LED_REGS vary depending on how many
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+ * bits the chip supports.
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+ */
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+
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+#include <linux/module.h>
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+#include <linux/delay.h>
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+#include <linux/string.h>
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+#include <linux/ctype.h>
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+#include <linux/leds.h>
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+#include <linux/err.h>
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+#include <linux/i2c.h>
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+#include <linux/workqueue.h>
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+
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+/* LED select registers determine the source that drives LED outputs */
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+#define PCA955X_LS_LED_ON 0x0 /* Output LOW */
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+#define PCA955X_LS_LED_OFF 0x1 /* Output HI-Z */
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+#define PCA955X_LS_BLINK0 0x2 /* Blink at PWM0 rate */
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+#define PCA955X_LS_BLINK1 0x3 /* Blink at PWM1 rate */
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+
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+enum pca955x_type {
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+ pca9550,
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+ pca9551,
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+ pca9552,
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+ pca9553,
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+};
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+
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+struct pca955x_chipdef {
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+ int bits;
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+ u8 slv_addr; /* 7-bit slave address mask */
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+ int slv_addr_shift; /* Number of bits to ignore */
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+};
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+
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+static struct pca955x_chipdef pca955x_chipdefs[] = {
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+ [pca9550] = {
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+ .bits = 2,
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+ .slv_addr = /* 110000x */ 0x60,
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+ .slv_addr_shift = 1,
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+ },
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+ [pca9551] = {
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+ .bits = 8,
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+ .slv_addr = /* 1100xxx */ 0x60,
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+ .slv_addr_shift = 3,
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+ },
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+ [pca9552] = {
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+ .bits = 16,
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+ .slv_addr = /* 1100xxx */ 0x60,
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+ .slv_addr_shift = 3,
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+ },
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+ [pca9553] = {
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+ .bits = 4,
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+ .slv_addr = /* 110001x */ 0x62,
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+ .slv_addr_shift = 1,
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+ },
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+};
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+
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+static const struct i2c_device_id pca955x_id[] = {
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+ { "pca9550", pca9550 },
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+ { "pca9551", pca9551 },
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+ { "pca9552", pca9552 },
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+ { "pca9553", pca9553 },
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+ { }
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+};
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+MODULE_DEVICE_TABLE(i2c, pca955x_id);
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+
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+struct pca955x_led {
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+ struct pca955x_chipdef *chipdef;
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+ struct i2c_client *client;
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+ struct work_struct work;
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+ spinlock_t lock;
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+ enum led_brightness brightness;
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+ struct led_classdev led_cdev;
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+ int led_num; /* 0 .. 15 potentially */
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+ char name[32];
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+};
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+
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+/* 8 bits per input register */
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+static inline int pca95xx_num_input_regs(int bits)
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+{
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+ return (bits + 7) / 8;
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+}
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+
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+/* 4 bits per LED selector register */
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+static inline int pca95xx_num_led_regs(int bits)
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+{
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+ return (bits + 3) / 4;
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+}
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+
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+/*
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+ * Return an LED selector register value based on an existing one, with
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+ * the appropriate 2-bit state value set for the given LED number (0-3).
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+ */
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+static inline u8 pca955x_ledsel(u8 oldval, int led_num, int state)
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+{
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+ return (oldval & (~(0x3 << (led_num << 1)))) |
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+ ((state & 0x3) << (led_num << 1));
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+}
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+
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+/*
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+ * Write to frequency prescaler register, used to program the
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+ * period of the PWM output. period = (PSCx + 1) / 38
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+ */
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+static void pca955x_write_psc(struct i2c_client *client, int n, u8 val)
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+{
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+ struct pca955x_led *pca955x = i2c_get_clientdata(client);
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+
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+ i2c_smbus_write_byte_data(client,
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+ pca95xx_num_input_regs(pca955x->chipdef->bits) + 2*n,
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+ val);
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+}
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+
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+/*
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+ * Write to PWM register, which determines the duty cycle of the
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+ * output. LED is OFF when the count is less than the value of this
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+ * register, and ON when it is greater. If PWMx == 0, LED is always OFF.
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+ *
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+ * Duty cycle is (256 - PWMx) / 256
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+ */
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+static void pca955x_write_pwm(struct i2c_client *client, int n, u8 val)
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+{
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+ struct pca955x_led *pca955x = i2c_get_clientdata(client);
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+
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+ i2c_smbus_write_byte_data(client,
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+ pca95xx_num_input_regs(pca955x->chipdef->bits) + 1 + 2*n,
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+ val);
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+}
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+
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+/*
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+ * Write to LED selector register, which determines the source that
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+ * drives the LED output.
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+ */
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+static void pca955x_write_ls(struct i2c_client *client, int n, u8 val)
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+{
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+ struct pca955x_led *pca955x = i2c_get_clientdata(client);
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+
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+ i2c_smbus_write_byte_data(client,
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+ pca95xx_num_input_regs(pca955x->chipdef->bits) + 4 + n,
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+ val);
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+}
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+
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+/*
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+ * Read the LED selector register, which determines the source that
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+ * drives the LED output.
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+ */
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+static u8 pca955x_read_ls(struct i2c_client *client, int n)
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+{
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+ struct pca955x_led *pca955x = i2c_get_clientdata(client);
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+
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+ return (u8) i2c_smbus_read_byte_data(client,
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+ pca95xx_num_input_regs(pca955x->chipdef->bits) + 4 + n);
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+}
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+
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+static void pca955x_led_work(struct work_struct *work)
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+{
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+ struct pca955x_led *pca955x;
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+ u8 ls;
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+ int chip_ls; /* which LSx to use (0-3 potentially) */
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+ int ls_led; /* which set of bits within LSx to use (0-3) */
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+
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+ pca955x = container_of(work, struct pca955x_led, work);
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+ chip_ls = pca955x->led_num / 4;
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+ ls_led = pca955x->led_num % 4;
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+
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+ ls = pca955x_read_ls(pca955x->client, chip_ls);
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+
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+ switch (pca955x->brightness) {
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+ case LED_FULL:
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+ ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_LED_ON);
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+ break;
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+ case LED_OFF:
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+ ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_LED_OFF);
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+ break;
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+ case LED_HALF:
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+ ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_BLINK0);
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+ break;
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+ default:
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+ /*
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+ * Use PWM1 for all other values. This has the unwanted
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+ * side effect of making all LEDs on the chip share the
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+ * same brightness level if set to a value other than
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+ * OFF, HALF, or FULL. But, this is probably better than
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+ * just turning off for all other values.
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+ */
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+ pca955x_write_pwm(pca955x->client, 1, 255-pca955x->brightness);
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+ ls = pca955x_ledsel(ls, ls_led, PCA955X_LS_BLINK1);
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+ break;
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+ }
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+
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+ pca955x_write_ls(pca955x->client, chip_ls, ls);
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+}
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+
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+void pca955x_led_set(struct led_classdev *led_cdev, enum led_brightness value)
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+{
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+ struct pca955x_led *pca955x;
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+
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+ pca955x = container_of(led_cdev, struct pca955x_led, led_cdev);
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+
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+ spin_lock(&pca955x->lock);
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+ pca955x->brightness = value;
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+
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+ /*
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+ * Must use workqueue for the actual I/O since I2C operations
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+ * can sleep.
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+ */
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+ schedule_work(&pca955x->work);
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+
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+ spin_unlock(&pca955x->lock);
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+}
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+
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+static int __devinit pca955x_probe(struct i2c_client *client,
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+ const struct i2c_device_id *id)
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+{
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+ struct pca955x_led *pca955x;
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+ int i;
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+ int err = -ENODEV;
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+ struct pca955x_chipdef *chip;
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+ struct i2c_adapter *adapter;
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+ struct led_platform_data *pdata;
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+
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+ chip = &pca955x_chipdefs[id->driver_data];
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+ adapter = to_i2c_adapter(client->dev.parent);
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+ pdata = client->dev.platform_data;
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+
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+ /* Make sure the slave address / chip type combo given is possible */
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+ if ((client->addr & ~((1 << chip->slv_addr_shift) - 1)) !=
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+ chip->slv_addr) {
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+ dev_err(&client->dev, "invalid slave address %02x\n",
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+ client->addr);
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+ return -ENODEV;
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+ }
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+
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+ printk(KERN_INFO "leds-pca955x: Using %s %d-bit LED driver at "
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+ "slave address 0x%02x\n",
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+ id->name, chip->bits, client->addr);
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+
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+ if (!i2c_check_functionality(adapter, I2C_FUNC_I2C))
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+ return -EIO;
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+
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+ if (pdata) {
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+ if (pdata->num_leds != chip->bits) {
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+ dev_err(&client->dev, "board info claims %d LEDs"
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+ " on a %d-bit chip\n",
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+ pdata->num_leds, chip->bits);
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+ return -ENODEV;
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+ }
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+ }
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+
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+ for (i = 0; i < chip->bits; i++) {
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+ pca955x = kzalloc(sizeof(struct pca955x_led), GFP_KERNEL);
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+ if (!pca955x) {
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+ err = -ENOMEM;
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+ goto exit;
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+ }
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+
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+ pca955x->chipdef = chip;
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+ pca955x->client = client;
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+ pca955x->led_num = i;
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+ /* Platform data can specify LED names and default triggers */
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+ if (pdata) {
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+ if (pdata->leds[i].name)
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+ snprintf(pca955x->name, 32, "pca955x:%s",
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+ pdata->leds[i].name);
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+ if (pdata->leds[i].default_trigger)
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+ pca955x->led_cdev.default_trigger =
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+ pdata->leds[i].default_trigger;
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+ } else {
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+ snprintf(pca955x->name, 32, "pca955x:%d", i);
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+ }
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+ spin_lock_init(&pca955x->lock);
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+
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+ pca955x->led_cdev.name = pca955x->name;
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+ pca955x->led_cdev.brightness_set =
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+ pca955x_led_set;
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+
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+ /*
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+ * Client data is a pointer to the _first_ pca955x_led
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+ * struct
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+ */
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+ if (i == 0)
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+ i2c_set_clientdata(client, pca955x);
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+
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+ INIT_WORK(&(pca955x->work), pca955x_led_work);
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+
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+ led_classdev_register(&client->dev, &(pca955x->led_cdev));
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+ }
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+
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+ /* Turn off LEDs */
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+ for (i = 0; i < pca95xx_num_led_regs(chip->bits); i++)
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+ pca955x_write_ls(client, i, 0x55);
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+
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+ /* PWM0 is used for half brightness or 50% duty cycle */
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+ pca955x_write_pwm(client, 0, 255-LED_HALF);
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+
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+ /* PWM1 is used for variable brightness, default to OFF */
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+ pca955x_write_pwm(client, 1, 0);
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+
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+ /* Set to fast frequency so we do not see flashing */
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+ pca955x_write_psc(client, 0, 0);
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+ pca955x_write_psc(client, 1, 0);
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+
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+ return 0;
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+exit:
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+ return err;
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+}
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+
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+static int __devexit pca955x_remove(struct i2c_client *client)
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+{
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+ struct pca955x_led *pca955x = i2c_get_clientdata(client);
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+ int leds = pca955x->chipdef->bits;
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+ int i;
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+
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+ for (i = 0; i < leds; i++) {
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+ led_classdev_unregister(&(pca955x->led_cdev));
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+ cancel_work_sync(&(pca955x->work));
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+ kfree(pca955x);
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+ pca955x = pca955x + 1;
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+ }
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+
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+ return 0;
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+}
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+
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+static struct i2c_driver pca955x_driver = {
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+ .driver = {
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+ .name = "leds-pca955x",
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+ .owner = THIS_MODULE,
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+ },
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+ .probe = pca955x_probe,
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+ .remove = __devexit_p(pca955x_remove),
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+ .id_table = pca955x_id,
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+};
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+
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+static int __init pca955x_leds_init(void)
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+{
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+ return i2c_add_driver(&pca955x_driver);
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+}
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+
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+static void __exit pca955x_leds_exit(void)
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+{
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+ i2c_del_driver(&pca955x_driver);
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+}
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+
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+module_init(pca955x_leds_init);
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+module_exit(pca955x_leds_exit);
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+
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+MODULE_AUTHOR("Nate Case <ncase@xes-inc.com>");
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+MODULE_DESCRIPTION("PCA955x LED driver");
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+MODULE_LICENSE("GPL v2");
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Linus Torvalds