[PATCH] i2c: stm32f7_i2c: allows for any bus frequency
Patrice CHOTARD
patrice.chotard at st.com
Wed Mar 18 10:56:09 CET 2020
On 3/6/20 11:09 AM, Patrick Delaunay wrote:
> From: Alain Volmat <alain.volmat at st.com>
>
> Do not limit to 3 (100KHz, 400KHz, 1MHz) bus frequencies, but
> instead allow for any frequency. Depending on the requested
> frequency (via the clock-frequency DT entry), use the spec
> data from either Standard, Fast or Fast Plus mode.
>
> In order to do so, the driver do not use anymore spec identifier
> by directly handle the requested frequency and from it retrieve
> the corresponding spec data to be used for the computation
> of the timing register.
>
> Signed-off-by: Alain Volmat <alain.volmat at st.com>
> Reviewed-by: Patrick DELAUNAY <patrick.delaunay at st.com>
> Signed-off-by: Patrick Delaunay <patrick.delaunay at st.com>
> ---
>
> drivers/i2c/stm32f7_i2c.c | 105 +++++++++++++++++++++-----------------
> 1 file changed, 59 insertions(+), 46 deletions(-)
>
> diff --git a/drivers/i2c/stm32f7_i2c.c b/drivers/i2c/stm32f7_i2c.c
> index 7d046c1a1e..fc5c1221e1 100644
> --- a/drivers/i2c/stm32f7_i2c.c
> +++ b/drivers/i2c/stm32f7_i2c.c
> @@ -7,10 +7,10 @@
> #include <clk.h>
> #include <dm.h>
> #include <i2c.h>
> -#include <malloc.h>
> #include <reset.h>
>
> #include <dm/device.h>
> +#include <linux/err.h>
> #include <linux/io.h>
>
> /* STM32 I2C registers */
> @@ -145,7 +145,6 @@ struct stm32_i2c_spec {
>
> /**
> * struct stm32_i2c_setup - private I2C timing setup parameters
> - * @speed: I2C speed mode (standard, Fast Plus)
> * @speed_freq: I2C speed frequency (Hz)
> * @clock_src: I2C clock source frequency (Hz)
> * @rise_time: Rise time (ns)
> @@ -154,7 +153,6 @@ struct stm32_i2c_spec {
> * @analog_filter: Analog filter delay (On/Off)
> */
> struct stm32_i2c_setup {
> - enum i2c_speed_mode speed;
> u32 speed_freq;
> u32 clock_src;
> u32 rise_time;
> @@ -184,10 +182,11 @@ struct stm32_i2c_priv {
> struct stm32_i2c_regs *regs;
> struct clk clk;
> struct stm32_i2c_setup *setup;
> - int speed;
> + u32 speed;
> };
>
> static const struct stm32_i2c_spec i2c_specs[] = {
> + /* Standard speed - 100 KHz */
> [IC_SPEED_MODE_STANDARD] = {
> .rate = I2C_SPEED_STANDARD_RATE,
> .rate_min = 8000,
> @@ -200,6 +199,7 @@ static const struct stm32_i2c_spec i2c_specs[] = {
> .l_min = 4700,
> .h_min = 4000,
> },
> + /* Fast speed - 400 KHz */
> [IC_SPEED_MODE_FAST] = {
> .rate = I2C_SPEED_FAST_RATE,
> .rate_min = 320000,
> @@ -212,6 +212,7 @@ static const struct stm32_i2c_spec i2c_specs[] = {
> .l_min = 1300,
> .h_min = 600,
> },
> + /* Fast Plus Speed - 1 MHz */
> [IC_SPEED_MODE_FAST_PLUS] = {
> .rate = I2C_SPEED_FAST_PLUS_RATE,
> .rate_min = 800000,
> @@ -474,6 +475,7 @@ static int stm32_i2c_xfer(struct udevice *bus, struct i2c_msg *msg,
> }
>
> static int stm32_i2c_compute_solutions(struct stm32_i2c_setup *setup,
> + const struct stm32_i2c_spec *specs,
> struct list_head *solutions)
> {
> struct stm32_i2c_timings *v;
> @@ -490,13 +492,13 @@ static int stm32_i2c_compute_solutions(struct stm32_i2c_setup *setup,
> af_delay_max = setup->analog_filter ?
> STM32_I2C_ANALOG_FILTER_DELAY_MAX : 0;
>
> - sdadel_min = i2c_specs[setup->speed].hddat_min + setup->fall_time -
> + sdadel_min = specs->hddat_min + setup->fall_time -
> af_delay_min - (setup->dnf + 3) * i2cclk;
>
> - sdadel_max = i2c_specs[setup->speed].vddat_max - setup->rise_time -
> + sdadel_max = specs->vddat_max - setup->rise_time -
> af_delay_max - (setup->dnf + 4) * i2cclk;
>
> - scldel_min = setup->rise_time + i2c_specs[setup->speed].sudat_min;
> + scldel_min = setup->rise_time + specs->sudat_min;
>
> if (sdadel_min < 0)
> sdadel_min = 0;
> @@ -548,6 +550,7 @@ static int stm32_i2c_compute_solutions(struct stm32_i2c_setup *setup,
> }
>
> static int stm32_i2c_choose_solution(struct stm32_i2c_setup *setup,
> + const struct stm32_i2c_spec *specs,
> struct list_head *solutions,
> struct stm32_i2c_timings *s)
> {
> @@ -570,8 +573,8 @@ static int stm32_i2c_choose_solution(struct stm32_i2c_setup *setup,
> dnf_delay = setup->dnf * i2cclk;
>
> tsync = af_delay_min + dnf_delay + (2 * i2cclk);
> - clk_max = STM32_NSEC_PER_SEC / i2c_specs[setup->speed].rate_min;
> - clk_min = STM32_NSEC_PER_SEC / i2c_specs[setup->speed].rate_max;
> + clk_max = STM32_NSEC_PER_SEC / specs->rate_min;
> + clk_min = STM32_NSEC_PER_SEC / specs->rate_max;
>
> /*
> * Among Prescaler possibilities discovered above figures out SCL Low
> @@ -589,7 +592,7 @@ static int stm32_i2c_choose_solution(struct stm32_i2c_setup *setup,
> for (l = 0; l < STM32_SCLL_MAX; l++) {
> u32 tscl_l = (l + 1) * prescaler + tsync;
>
> - if ((tscl_l < i2c_specs[setup->speed].l_min) ||
> + if (tscl_l < specs->l_min ||
> (i2cclk >=
> ((tscl_l - af_delay_min - dnf_delay) / 4))) {
> continue;
> @@ -601,7 +604,7 @@ static int stm32_i2c_choose_solution(struct stm32_i2c_setup *setup,
> setup->rise_time + setup->fall_time;
>
> if ((tscl >= clk_min) && (tscl <= clk_max) &&
> - (tscl_h >= i2c_specs[setup->speed].h_min) &&
> + (tscl_h >= specs->h_min) &&
> (i2cclk < tscl_h)) {
> u32 clk_error;
>
> @@ -630,26 +633,40 @@ static int stm32_i2c_choose_solution(struct stm32_i2c_setup *setup,
> return ret;
> }
>
> +static const struct stm32_i2c_spec *get_specs(u32 rate)
> +{
> + unsigned int i;
> +
> + for (i = 0; i < ARRAY_SIZE(i2c_specs); i++)
> + if (rate <= i2c_specs[i].rate)
> + return &i2c_specs[i];
> +
> + /* NOT REACHED */
> + return ERR_PTR(-EINVAL);
> +}
> +
> static int stm32_i2c_compute_timing(struct stm32_i2c_priv *i2c_priv,
> struct stm32_i2c_setup *setup,
> struct stm32_i2c_timings *output)
> {
> + const struct stm32_i2c_spec *specs;
> struct stm32_i2c_timings *v, *_v;
> struct list_head solutions;
> int ret;
>
> - if (setup->speed >= ARRAY_SIZE(i2c_specs)) {
> - pr_err("%s: speed out of bound {%d/%d}\n", __func__,
> - setup->speed, ARRAY_SIZE(i2c_specs) - 1);
> + specs = get_specs(setup->speed_freq);
> + if (specs == ERR_PTR(-EINVAL)) {
> + pr_err("%s: speed out of bound {%d}\n", __func__,
> + setup->speed_freq);
> return -EINVAL;
> }
>
> - if ((setup->rise_time > i2c_specs[setup->speed].rise_max) ||
> - (setup->fall_time > i2c_specs[setup->speed].fall_max)) {
> + if (setup->rise_time > specs->rise_max ||
> + setup->fall_time > specs->fall_max) {
> pr_err("%s :timings out of bound Rise{%d>%d}/Fall{%d>%d}\n",
> __func__,
> - setup->rise_time, i2c_specs[setup->speed].rise_max,
> - setup->fall_time, i2c_specs[setup->speed].fall_max);
> + setup->rise_time, specs->rise_max,
> + setup->fall_time, specs->fall_max);
> return -EINVAL;
> }
>
> @@ -659,18 +676,12 @@ static int stm32_i2c_compute_timing(struct stm32_i2c_priv *i2c_priv,
> return -EINVAL;
> }
>
> - if (setup->speed_freq > i2c_specs[setup->speed].rate) {
> - pr_err("%s: Freq {%d/%d}\n", __func__,
> - setup->speed_freq, i2c_specs[setup->speed].rate);
> - return -EINVAL;
> - }
> -
> INIT_LIST_HEAD(&solutions);
> - ret = stm32_i2c_compute_solutions(setup, &solutions);
> + ret = stm32_i2c_compute_solutions(setup, specs, &solutions);
> if (ret)
> goto exit;
>
> - ret = stm32_i2c_choose_solution(setup, &solutions, output);
> + ret = stm32_i2c_choose_solution(setup, specs, &solutions, output);
> if (ret)
> goto exit;
>
> @@ -689,14 +700,24 @@ exit:
> return ret;
> }
>
> +static u32 get_lower_rate(u32 rate)
> +{
> + int i;
> +
> + for (i = ARRAY_SIZE(i2c_specs) - 1; i >= 0; i--)
> + if (rate > i2c_specs[i].rate)
> + return i2c_specs[i].rate;
> +
> + return i2c_specs[0].rate;
> +}
> +
> static int stm32_i2c_setup_timing(struct stm32_i2c_priv *i2c_priv,
> struct stm32_i2c_timings *timing)
> {
> struct stm32_i2c_setup *setup = i2c_priv->setup;
> int ret = 0;
>
> - setup->speed = i2c_priv->speed;
> - setup->speed_freq = i2c_specs[setup->speed].rate;
> + setup->speed_freq = i2c_priv->speed;
> setup->clock_src = clk_get_rate(&i2c_priv->clk);
>
> if (!setup->clock_src) {
> @@ -709,13 +730,11 @@ static int stm32_i2c_setup_timing(struct stm32_i2c_priv *i2c_priv,
> if (ret) {
> debug("%s: failed to compute I2C timings.\n",
> __func__);
> - if (i2c_priv->speed > IC_SPEED_MODE_STANDARD) {
> - i2c_priv->speed--;
> - setup->speed = i2c_priv->speed;
> + if (setup->speed_freq > I2C_SPEED_STANDARD_RATE) {
> setup->speed_freq =
> - i2c_specs[setup->speed].rate;
> + get_lower_rate(setup->speed_freq);
> debug("%s: downgrade I2C Speed Freq to (%i)\n",
> - __func__, i2c_specs[setup->speed].rate);
> + __func__, setup->speed_freq);
> } else {
> break;
> }
> @@ -727,13 +746,15 @@ static int stm32_i2c_setup_timing(struct stm32_i2c_priv *i2c_priv,
> return ret;
> }
>
> - debug("%s: I2C Speed(%i), Freq(%i), Clk Source(%i)\n", __func__,
> - setup->speed, setup->speed_freq, setup->clock_src);
> + debug("%s: I2C Freq(%i), Clk Source(%i)\n", __func__,
> + setup->speed_freq, setup->clock_src);
> debug("%s: I2C Rise(%i) and Fall(%i) Time\n", __func__,
> setup->rise_time, setup->fall_time);
> debug("%s: I2C Analog Filter(%s), DNF(%i)\n", __func__,
> setup->analog_filter ? "On" : "Off", setup->dnf);
>
> + i2c_priv->speed = setup->speed_freq;
> +
> return 0;
> }
>
> @@ -773,21 +794,13 @@ static int stm32_i2c_set_bus_speed(struct udevice *bus, unsigned int speed)
> {
> struct stm32_i2c_priv *i2c_priv = dev_get_priv(bus);
>
> - switch (speed) {
> - case I2C_SPEED_STANDARD_RATE:
> - i2c_priv->speed = IC_SPEED_MODE_STANDARD;
> - break;
> - case I2C_SPEED_FAST_RATE:
> - i2c_priv->speed = IC_SPEED_MODE_FAST;
> - break;
> - case I2C_SPEED_FAST_PLUS_RATE:
> - i2c_priv->speed = IC_SPEED_MODE_FAST_PLUS;
> - break;
> - default:
> + if (speed > I2C_SPEED_FAST_PLUS_RATE) {
> debug("%s: Speed %d not supported\n", __func__, speed);
> return -EINVAL;
> }
>
> + i2c_priv->speed = speed;
> +
> return stm32_i2c_hw_config(i2c_priv);
> }
>
Acked-by: Patrice Chotard <patrice.chotard at st.com>
Thanks
Patrice
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