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56 lines
1.6 KiB
56 lines
1.6 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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* Copyright 2012 DENX Software Engineering, GmbH |
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* |
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* Pulled from code: |
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* Portions copyright (C) 2003 Russell King, PXA MMCI Driver |
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* Portions copyright (C) 2004-2005 Pierre Ossman, W83L51xD SD/MMC driver |
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* |
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* Copyright 2008 Embedded Alley Solutions, Inc. |
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* Copyright 2009-2011 Freescale Semiconductor, Inc. |
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*/ |
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#include <linux/kernel.h> |
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#include <linux/init.h> |
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#include <linux/clk.h> |
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#include <linux/module.h> |
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#include <linux/device.h> |
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#include <linux/io.h> |
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#include <linux/spi/mxs-spi.h> |
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void mxs_ssp_set_clk_rate(struct mxs_ssp *ssp, unsigned int rate) |
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{ |
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unsigned int ssp_clk, ssp_sck; |
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u32 clock_divide, clock_rate; |
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u32 val; |
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ssp_clk = clk_get_rate(ssp->clk); |
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for (clock_divide = 2; clock_divide <= 254; clock_divide += 2) { |
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clock_rate = DIV_ROUND_UP(ssp_clk, rate * clock_divide); |
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clock_rate = (clock_rate > 0) ? clock_rate - 1 : 0; |
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if (clock_rate <= 255) |
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break; |
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} |
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if (clock_divide > 254) { |
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dev_err(ssp->dev, |
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"%s: cannot set clock to %d\n", __func__, rate); |
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return; |
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} |
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ssp_sck = ssp_clk / clock_divide / (1 + clock_rate); |
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val = readl(ssp->base + HW_SSP_TIMING(ssp)); |
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val &= ~(BM_SSP_TIMING_CLOCK_DIVIDE | BM_SSP_TIMING_CLOCK_RATE); |
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val |= BF_SSP(clock_divide, TIMING_CLOCK_DIVIDE); |
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val |= BF_SSP(clock_rate, TIMING_CLOCK_RATE); |
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writel(val, ssp->base + HW_SSP_TIMING(ssp)); |
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ssp->clk_rate = ssp_sck; |
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dev_dbg(ssp->dev, |
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"%s: clock_divide %d, clock_rate %d, ssp_clk %d, rate_actual %d, rate_requested %d\n", |
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__func__, clock_divide, clock_rate, ssp_clk, ssp_sck, rate); |
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} |
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EXPORT_SYMBOL_GPL(mxs_ssp_set_clk_rate);
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