92 lines
2.8 KiB
Diff
92 lines
2.8 KiB
Diff
From b660279cc83aff2018cecfc3fb55757a8d64f607 Mon Sep 17 00:00:00 2001
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From: Phil Elwell <phil@raspberrypi.com>
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Date: Tue, 16 Jan 2024 15:54:22 +0000
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Subject: [PATCH 1257/1295] i2c: designware: Use SCL rise and fall times in DT
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Calculate the HCNT and LCNT values for all modes using the rise and
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fall times of SCL, the aim being a 50/50 mark/space ratio.
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Signed-off-by: Phil Elwell <phil@raspberrypi.com>
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---
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drivers/i2c/busses/i2c-designware-master.c | 26 ++++++++++++++++++++++
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1 file changed, 26 insertions(+)
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--- a/drivers/i2c/busses/i2c-designware-master.c
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+++ b/drivers/i2c/busses/i2c-designware-master.c
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@@ -16,6 +16,7 @@
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#include <linux/i2c.h>
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#include <linux/interrupt.h>
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#include <linux/io.h>
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+#include <linux/math64.h>
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#include <linux/module.h>
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#include <linux/pm_runtime.h>
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#include <linux/regmap.h>
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@@ -37,6 +38,22 @@ static void i2c_dw_configure_fifo_master
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regmap_write(dev->map, DW_IC_CON, dev->master_cfg);
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}
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+static u16 clock_calc(struct dw_i2c_dev *dev, bool want_high)
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+{
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+ struct i2c_timings *t = &dev->timings;
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+ u32 wanted_speed = t->bus_freq_hz;
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+ u32 clk_khz = i2c_dw_clk_rate(dev);
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+ u32 extra_ns = want_high ? t->scl_fall_ns : t->scl_rise_ns;
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+ u32 extra_cycles = (u32)div_u64((u64)clk_khz * extra_ns, 1000000);
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+ u32 period = div_u64((u64)clk_khz * 1000 + wanted_speed - 1, wanted_speed);
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+ u32 cycles = (period + want_high)/2 - extra_cycles;
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+
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+ if (cycles > 0xffff)
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+ cycles = 0xffff;
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+
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+ return (u16)cycles;
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+}
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+
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static int i2c_dw_set_timings_master(struct dw_i2c_dev *dev)
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{
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u32 comp_param1;
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@@ -44,6 +61,7 @@ static int i2c_dw_set_timings_master(str
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struct i2c_timings *t = &dev->timings;
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const char *fp_str = "";
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u32 ic_clk;
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+ u32 hcnt, lcnt;
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int ret;
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ret = i2c_dw_acquire_lock(dev);
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@@ -59,6 +77,9 @@ static int i2c_dw_set_timings_master(str
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sda_falling_time = t->sda_fall_ns ?: 300; /* ns */
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scl_falling_time = t->scl_fall_ns ?: 300; /* ns */
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+ hcnt = clock_calc(dev, true);
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+ lcnt = clock_calc(dev, false);
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+
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/* Calculate SCL timing parameters for standard mode if not set */
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if (!dev->ss_hcnt || !dev->ss_lcnt) {
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ic_clk = i2c_dw_clk_rate(dev);
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@@ -74,6 +95,8 @@ static int i2c_dw_set_timings_master(str
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scl_falling_time,
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0); /* No offset */
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}
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+ dev->ss_hcnt = hcnt;
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+ dev->ss_lcnt = lcnt;
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dev_dbg(dev->dev, "Standard Mode HCNT:LCNT = %d:%d\n",
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dev->ss_hcnt, dev->ss_lcnt);
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@@ -124,6 +147,8 @@ static int i2c_dw_set_timings_master(str
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scl_falling_time,
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0); /* No offset */
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}
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+ dev->fs_hcnt = hcnt;
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+ dev->fs_lcnt = lcnt;
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dev_dbg(dev->dev, "Fast Mode%s HCNT:LCNT = %d:%d\n",
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fp_str, dev->fs_hcnt, dev->fs_lcnt);
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@@ -152,6 +177,8 @@ static int i2c_dw_set_timings_master(str
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scl_falling_time,
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0); /* No offset */
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}
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+ dev->hs_hcnt = hcnt;
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+ dev->hs_lcnt = lcnt;
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dev_dbg(dev->dev, "High Speed Mode HCNT:LCNT = %d:%d\n",
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dev->hs_hcnt, dev->hs_lcnt);
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}
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