mirror of
https://github.com/Ysurac/openmptcprouter.git
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124 lines
4.2 KiB
Diff
124 lines
4.2 KiB
Diff
From 23087d3f29adf1bd2b53111b9e61f8935fdbcf47 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 16:03:14 +0000
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Subject: [PATCH 417/697] i2c: designware: Support non-standard bus speeds
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Add support for non-standard bus speeds by treating them as detuned
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versions of the slowest standard speed not less than the requested
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speed.
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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-common.c | 27 ++++++++++++++++
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drivers/i2c/busses/i2c-designware-core.h | 1 +
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drivers/i2c/busses/i2c-designware-master.c | 37 ++++++++++++++--------
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3 files changed, 52 insertions(+), 13 deletions(-)
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--- a/drivers/i2c/busses/i2c-designware-common.c
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+++ b/drivers/i2c/busses/i2c-designware-common.c
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@@ -359,6 +359,9 @@ static void i2c_dw_adjust_bus_speed(stru
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{
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u32 acpi_speed = i2c_dw_acpi_round_bus_speed(dev->dev);
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struct i2c_timings *t = &dev->timings;
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+ u32 wanted_speed;
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+ u32 legal_speed = 0;
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+ int i;
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/*
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* Find bus speed from the "clock-frequency" device property, ACPI
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@@ -370,6 +373,30 @@ static void i2c_dw_adjust_bus_speed(stru
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t->bus_freq_hz = max(t->bus_freq_hz, acpi_speed);
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else
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t->bus_freq_hz = I2C_MAX_FAST_MODE_FREQ;
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+
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+ wanted_speed = t->bus_freq_hz;
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+
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+ /* For unsupported speeds, scale down the lowest speed which is faster. */
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+ for (i = 0; i < ARRAY_SIZE(supported_speeds); i++) {
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+ /* supported speeds is in decreasing order */
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+ if (wanted_speed == supported_speeds[i]) {
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+ legal_speed = 0;
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+ break;
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+ }
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+ if (wanted_speed > supported_speeds[i])
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+ break;
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+
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+ legal_speed = supported_speeds[i];
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+ }
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+
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+ if (legal_speed) {
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+ /*
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+ * Pretend this was the requested speed, but preserve the preferred
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+ * speed so the clock counts can be scaled.
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+ */
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+ t->bus_freq_hz = legal_speed;
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+ dev->wanted_bus_speed = wanted_speed;
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+ }
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}
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int i2c_dw_fw_parse_and_configure(struct dw_i2c_dev *dev)
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--- a/drivers/i2c/busses/i2c-designware-core.h
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+++ b/drivers/i2c/busses/i2c-designware-core.h
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@@ -293,6 +293,7 @@ struct dw_i2c_dev {
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u16 fp_lcnt;
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u16 hs_hcnt;
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u16 hs_lcnt;
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+ u32 wanted_bus_speed;
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int (*acquire_lock)(void);
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void (*release_lock)(void);
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int semaphore_idx;
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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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@@ -40,20 +40,32 @@ 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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+static u32 linear_interpolate(u32 x, u32 x1, u32 x2, u32 y1, u32 y2)
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+{
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+ return ((x - x1) * y2 + (x2 - x) * y1) / (x2 - x1);
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+}
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+
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+static u16 u16_clamp(u32 v)
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+{
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+ return (u16)min(v, 0xffff);
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+}
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+
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+static void clock_calc(struct dw_i2c_dev *dev, u32 *hcnt, u32 *lcnt)
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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 wanted_khz = (dev->wanted_bus_speed ?: t->bus_freq_hz)/1000;
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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)((u64)clk_khz * extra_ns / 1000000);
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- u32 period = ((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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+ u32 min_high_ns = (wanted_khz <= 100) ? 4000 :
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+ (wanted_khz <= 400) ?
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+ linear_interpolate(wanted_khz, 100, 400, 4000, 600) :
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+ linear_interpolate(wanted_khz, 400, 1000, 600, 260);
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+ u32 high_cycles = (u32)(((u64)clk_khz * min_high_ns + 999999) / 1000000) + 1;
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+ u32 extra_high_cycles = (u32)((u64)clk_khz * t->scl_fall_ns / 1000000);
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+ u32 extra_low_cycles = (u32)((u64)clk_khz * t->scl_rise_ns / 1000000);
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+ u32 period = ((u64)clk_khz + wanted_khz - 1) / wanted_khz;
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- return (u16)cycles;
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+ *hcnt = u16_clamp(high_cycles - extra_high_cycles);
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+ *lcnt = u16_clamp(period - high_cycles - extra_low_cycles);
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}
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static int i2c_dw_set_timings_master(struct dw_i2c_dev *dev)
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@@ -79,8 +91,7 @@ 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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+ clock_calc(dev, &hcnt, &lcnt);
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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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