add new system file

hc

2024-02-20 102a0743326a03cd1a1202ceda21e175b7d3575c

 kernel/drivers/spi/spi-tegra20-slink.c
..
..
@@ -1,19 +1,8 @@
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+// SPDX-License-Identifier: GPL-2.0-only
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 /*
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  * SPI driver for Nvidia's Tegra20/Tegra30 SLINK Controller.
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  *
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  * Copyright (c) 2012, NVIDIA CORPORATION.  All rights reserved.
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- *
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- * This program is free software; you can redistribute it and/or modify it
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- * under the terms and conditions of the GNU General Public License,
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- * version 2, as published by the Free Software Foundation.
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- *
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- * This program is distributed in the hope it will be useful, but WITHOUT
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- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
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- * more details.
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- *
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- * You should have received a copy of the GNU General Public License
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- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
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  */
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7
 
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 #include <linux/clk.h>
..
..
@@ -610,15 +599,10 @@
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 	int ret;
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 	struct dma_slave_config dma_sconfig;
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-	dma_chan = dma_request_slave_channel_reason(tspi->dev,
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-						dma_to_memory ? "rx" : "tx");
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-	if (IS_ERR(dma_chan)) {
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-		ret = PTR_ERR(dma_chan);
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-		if (ret != -EPROBE_DEFER)
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-			dev_err(tspi->dev,
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-				"Dma channel is not available: %d\n", ret);
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-		return ret;
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-	}
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+	dma_chan = dma_request_chan(tspi->dev, dma_to_memory ? "rx" : "tx");
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+	if (IS_ERR(dma_chan))
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+		return dev_err_probe(tspi->dev, PTR_ERR(dma_chan),
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+				     "Dma channel is not available\n");
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 	dma_buf = dma_alloc_coherent(tspi->dev, tspi->dma_buf_size,
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 				&dma_phys, GFP_KERNEL);
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@@ -717,9 +701,6 @@
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 	command2 = tspi->command2_reg;
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 	command2 &= ~(SLINK_RXEN | SLINK_TXEN);
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-	tegra_slink_writel(tspi, command, SLINK_COMMAND);
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-	tspi->command_reg = command;
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-
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 	tspi->cur_direction = 0;
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 	if (t->rx_buf) {
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 		command2 |= SLINK_RXEN;
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@@ -729,8 +710,17 @@
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 		command2 |= SLINK_TXEN;
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 		tspi->cur_direction |= DATA_DIR_TX;
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 	}
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+
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+	/*
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+	 * Writing to the command2 register bevore the command register prevents
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+	 * a spike in chip_select line 0. This selects the chip_select line
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+	 * before changing the chip_select value.
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+	 */
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 	tegra_slink_writel(tspi, command2, SLINK_COMMAND2);
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 	tspi->command2_reg = command2;
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+
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+	tegra_slink_writel(tspi, command, SLINK_COMMAND);
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+	tspi->command_reg = command;
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 	if (total_fifo_words > SLINK_FIFO_DEPTH)
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 		ret = tegra_slink_start_dma_based_transfer(tspi, t);
..
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@@ -1016,14 +1006,8 @@
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 	struct resource		*r;
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 	int ret, spi_irq;
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 	const struct tegra_slink_chip_data *cdata = NULL;
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-	const struct of_device_id *match;
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-	match = of_match_device(tegra_slink_of_match, &pdev->dev);
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-	if (!match) {
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-		dev_err(&pdev->dev, "Error: No device match found\n");
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-		return -ENODEV;
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-	}
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-	cdata = match->data;
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+	cdata = of_device_get_match_data(&pdev->dev);
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 	master = spi_alloc_master(&pdev->dev, sizeof(*tspi));
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 	if (!master) {
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@@ -1125,6 +1109,7 @@
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 	ret = pm_runtime_get_sync(&pdev->dev);
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 	if (ret < 0) {
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 		dev_err(&pdev->dev, "pm runtime get failed, e = %d\n", ret);
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+		pm_runtime_put_noidle(&pdev->dev);
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 		goto exit_pm_disable;
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 	}
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 	tspi->def_command_reg  = SLINK_M_S;