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7d2600b9cc
Use devm_platform_ioremap_resource() to simplify the code a bit. This is detected by coccinelle. Reported-by: Hulk Robot <hulkci@huawei.com> Signed-off-by: YueHaibing <yuehaibing@huawei.com> Link: https://lore.kernel.org/r/20190904135918.25352-15-yuehaibing@huawei.com Signed-off-by: Mark Brown <broonie@kernel.org>
246 lines
5.4 KiB
C
246 lines
5.4 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* SPI master driver for ICP DAS LP-8841 RTC
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*
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* Copyright (C) 2016 Sergei Ianovich
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*
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* based on
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*
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* Dallas DS1302 RTC Support
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* Copyright (C) 2002 David McCullough
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* Copyright (C) 2003 - 2007 Paul Mundt
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*/
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#include <linux/delay.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/platform_device.h>
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#include <linux/of.h>
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#include <linux/of_device.h>
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#include <linux/spi/spi.h>
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#define DRIVER_NAME "spi_lp8841_rtc"
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#define SPI_LP8841_RTC_CE 0x01
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#define SPI_LP8841_RTC_CLK 0x02
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#define SPI_LP8841_RTC_nWE 0x04
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#define SPI_LP8841_RTC_MOSI 0x08
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#define SPI_LP8841_RTC_MISO 0x01
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/*
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* REVISIT If there is support for SPI_3WIRE and SPI_LSB_FIRST in SPI
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* GPIO driver, this SPI driver can be replaced by a simple GPIO driver
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* providing 3 GPIO pins.
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*/
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struct spi_lp8841_rtc {
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void *iomem;
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unsigned long state;
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};
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static inline void
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setsck(struct spi_lp8841_rtc *data, int is_on)
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{
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if (is_on)
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data->state |= SPI_LP8841_RTC_CLK;
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else
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data->state &= ~SPI_LP8841_RTC_CLK;
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writeb(data->state, data->iomem);
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}
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static inline void
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setmosi(struct spi_lp8841_rtc *data, int is_on)
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{
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if (is_on)
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data->state |= SPI_LP8841_RTC_MOSI;
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else
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data->state &= ~SPI_LP8841_RTC_MOSI;
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writeb(data->state, data->iomem);
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}
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static inline int
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getmiso(struct spi_lp8841_rtc *data)
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{
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return ioread8(data->iomem) & SPI_LP8841_RTC_MISO;
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}
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static inline u32
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bitbang_txrx_be_cpha0_lsb(struct spi_lp8841_rtc *data,
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unsigned usecs, unsigned cpol, unsigned flags,
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u32 word, u8 bits)
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{
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/* if (cpol == 0) this is SPI_MODE_0; else this is SPI_MODE_2 */
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u32 shift = 32 - bits;
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/* clock starts at inactive polarity */
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for (; likely(bits); bits--) {
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/* setup LSB (to slave) on leading edge */
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if ((flags & SPI_MASTER_NO_TX) == 0)
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setmosi(data, (word & 1));
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usleep_range(usecs, usecs + 1); /* T(setup) */
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/* sample LSB (from slave) on trailing edge */
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word >>= 1;
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if ((flags & SPI_MASTER_NO_RX) == 0)
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word |= (getmiso(data) << 31);
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setsck(data, !cpol);
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usleep_range(usecs, usecs + 1);
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setsck(data, cpol);
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}
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word >>= shift;
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return word;
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}
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static int
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spi_lp8841_rtc_transfer_one(struct spi_master *master,
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struct spi_device *spi,
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struct spi_transfer *t)
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{
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struct spi_lp8841_rtc *data = spi_master_get_devdata(master);
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unsigned count = t->len;
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const u8 *tx = t->tx_buf;
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u8 *rx = t->rx_buf;
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u8 word = 0;
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int ret = 0;
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if (tx) {
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data->state &= ~SPI_LP8841_RTC_nWE;
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writeb(data->state, data->iomem);
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while (likely(count > 0)) {
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word = *tx++;
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bitbang_txrx_be_cpha0_lsb(data, 1, 0,
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SPI_MASTER_NO_RX, word, 8);
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count--;
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}
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} else if (rx) {
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data->state |= SPI_LP8841_RTC_nWE;
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writeb(data->state, data->iomem);
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while (likely(count > 0)) {
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word = bitbang_txrx_be_cpha0_lsb(data, 1, 0,
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SPI_MASTER_NO_TX, word, 8);
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*rx++ = word;
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count--;
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}
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} else {
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ret = -EINVAL;
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}
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spi_finalize_current_transfer(master);
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return ret;
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}
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static void
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spi_lp8841_rtc_set_cs(struct spi_device *spi, bool enable)
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{
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struct spi_lp8841_rtc *data = spi_master_get_devdata(spi->master);
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data->state = 0;
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writeb(data->state, data->iomem);
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if (enable) {
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usleep_range(4, 5);
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data->state |= SPI_LP8841_RTC_CE;
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writeb(data->state, data->iomem);
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usleep_range(4, 5);
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}
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}
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static int
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spi_lp8841_rtc_setup(struct spi_device *spi)
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{
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if ((spi->mode & SPI_CS_HIGH) == 0) {
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dev_err(&spi->dev, "unsupported active low chip select\n");
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return -EINVAL;
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}
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if ((spi->mode & SPI_LSB_FIRST) == 0) {
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dev_err(&spi->dev, "unsupported MSB first mode\n");
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return -EINVAL;
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}
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if ((spi->mode & SPI_3WIRE) == 0) {
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dev_err(&spi->dev, "unsupported wiring. 3 wires required\n");
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return -EINVAL;
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}
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return 0;
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}
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#ifdef CONFIG_OF
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static const struct of_device_id spi_lp8841_rtc_dt_ids[] = {
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{ .compatible = "icpdas,lp8841-spi-rtc" },
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{ }
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};
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MODULE_DEVICE_TABLE(of, spi_lp8841_rtc_dt_ids);
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#endif
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static int
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spi_lp8841_rtc_probe(struct platform_device *pdev)
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{
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int ret;
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struct spi_master *master;
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struct spi_lp8841_rtc *data;
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master = spi_alloc_master(&pdev->dev, sizeof(*data));
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if (!master)
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return -ENOMEM;
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platform_set_drvdata(pdev, master);
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master->flags = SPI_MASTER_HALF_DUPLEX;
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master->mode_bits = SPI_CS_HIGH | SPI_3WIRE | SPI_LSB_FIRST;
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master->bus_num = pdev->id;
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master->num_chipselect = 1;
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master->setup = spi_lp8841_rtc_setup;
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master->set_cs = spi_lp8841_rtc_set_cs;
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master->transfer_one = spi_lp8841_rtc_transfer_one;
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master->bits_per_word_mask = SPI_BPW_MASK(8);
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#ifdef CONFIG_OF
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master->dev.of_node = pdev->dev.of_node;
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#endif
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data = spi_master_get_devdata(master);
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data->iomem = devm_platform_ioremap_resource(pdev, 0);
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ret = PTR_ERR_OR_ZERO(data->iomem);
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if (ret) {
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dev_err(&pdev->dev, "failed to get IO address\n");
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goto err_put_master;
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}
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/* register with the SPI framework */
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ret = devm_spi_register_master(&pdev->dev, master);
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if (ret) {
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dev_err(&pdev->dev, "cannot register spi master\n");
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goto err_put_master;
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}
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return ret;
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err_put_master:
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spi_master_put(master);
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return ret;
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}
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MODULE_ALIAS("platform:" DRIVER_NAME);
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static struct platform_driver spi_lp8841_rtc_driver = {
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.driver = {
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.name = DRIVER_NAME,
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.of_match_table = of_match_ptr(spi_lp8841_rtc_dt_ids),
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},
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.probe = spi_lp8841_rtc_probe,
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};
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module_platform_driver(spi_lp8841_rtc_driver);
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MODULE_DESCRIPTION("SPI master driver for ICP DAS LP-8841 RTC");
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MODULE_AUTHOR("Sergei Ianovich");
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MODULE_LICENSE("GPL");
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