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Message-ID: <5698AF24.2030202@rock-chips.com>
Date: Fri, 15 Jan 2016 16:34:44 +0800
From: "David.Wu" <wdc@...k-chips.com>
To: Andy Shevchenko <andy.shevchenko@...il.com>,
David Wu <david.wu@...k-chips.com>
Cc: Heiko Stübner <heiko@...ech.de>,
Wolfram Sang <wsa@...-dreams.de>,
Douglas Anderson <dianders@...omium.org>,
Tao Huang <huangtao@...k-chips.com>,
Chris Zhong <zyw@...k-chips.com>, cf@...k-chips.com,
Jianqun Xu <xjq@...k-chips.com>, Lin Huang <hl@...k-chips.com>,
linux-arm Mailing List <linux-arm-kernel@...ts.infradead.org>,
linux-rockchip@...ts.infradead.org, linux-i2c@...r.kernel.org,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 2/4] i2c: rk3x: add ops to caculate i2c clocks
Hi Andy,
在 2016/1/14 21:19, Andy Shevchenko 写道:
> On Thu, Jan 14, 2016 at 2:31 PM, David Wu <david.wu@...k-chips.com> wrote:
>> From: David Wu <wdc@...k-chips.com>
>>
>> I2c Controller of rk3x is updated for the rules to caculate clocks.
>> So it need a new method to caculate i2c clock timing information
>> for new version. The current method is defined as v0, and new is
>> v1, next maybe v2......
> Thanks for an update. My comments below.
>
>> --- a/drivers/i2c/busses/i2c-rk3x.c
>> +++ b/drivers/i2c/busses/i2c-rk3x.c
>> @@ -90,10 +95,27 @@ struct rk3x_i2c_soc_data {
>> int grf_offset;
>> };
>>
>> +/**
>> + * struct rk3x_priv_i2c_timings - rk3x I2C timing information
>> + * @div_low: Divider output for low
>> + * @div_high: Divider output for high
>> + */
>> +struct rk3x_priv_i2c_timings {
>> + unsigned long div_low;
>> + unsigned long div_high;
>> +};
>> +
>> +struct rk3x_i2c_ops {
>> + int (*calc_clock)(unsigned long,
>> + struct i2c_timings *,
>> + struct rk3x_priv_i2c_timings *);
>> +};
>> +
>> struct rk3x_i2c {
>> struct i2c_adapter adap;
>> struct device *dev;
>> struct rk3x_i2c_soc_data *soc_data;
>> + struct rk3x_i2c_ops ops;
> Not much sense for now to have a struct for one member.
Yes, it looks ok not to do change here.
>> /* Hardware resources */
>> void __iomem *regs;
>> @@ -102,6 +124,7 @@ struct rk3x_i2c {
>>
> What about
> /* I2C timing settings */
> struct i2c_timings t;
>
> /* Divider settings */
> int (*calc_divs)(unsigned long,
> struct i2c_timings *,
> unsigned long *div_low,
> unsigned long *div_high);
> unsigned long div_low;
> unsigned long div_high;
> ?
>
> As far as I understand you still calculate divider values.
>
>> /* Synchronization & notification */
>> spinlock_t lock;
>> @@ -431,21 +454,20 @@ out:
>> }
>>
>> /**
>> - * Calculate divider values for desired SCL frequency
>> + * Calculate timing clock info values for desired SCL frequency
>> *
>> * @clk_rate: I2C input clock rate
>> - * @t_input: Known I2C timing information.
>> - * @div_low: Divider output for low
>> - * @div_high: Divider output for high
> For now seems better to leave this prototype.
>
>> + * @t_input: Known I2C timing information
>> + * @t_output: Caculated rk3x private timing information that would
>> + * be written into regs
>> *
>> * Returns: 0 on success, -EINVAL if the goal SCL rate is too slow. In that case
>> * a best-effort divider value is returned in divs. If the target rate is
>> * too high, we silently use the highest possible rate.
>> */
>> -static int rk3x_i2c_calc_divs(unsigned long clk_rate,
>> - struct i2c_timings *t_input,
>> - unsigned long *div_low,
>> - unsigned long *div_high)
>> +static int rk3x_i2c_v0_calc_clock(unsigned long clk_rate,
>> + struct i2c_timings *t_input,
>> + struct rk3x_priv_i2c_timings *t_output)
>> {
>> unsigned long spec_min_low_ns, spec_min_high_ns;
>> unsigned long spec_setup_start, spec_max_data_hold_ns;
>
>> @@ -583,25 +605,25 @@ static int rk3x_i2c_calc_divs(unsigned long clk_rate,
>>
>> /* Give low the "ideal" and give high whatever extra is left */
>> extra_low_div = ideal_low_div - min_low_div;
>> - *div_low = ideal_low_div;
>> - *div_high = min_high_div + (extra_div - extra_low_div);
>> + t_output->div_low = ideal_low_div;
>> + t_output->div_high = min_high_div + (extra_div - extra_low_div);
>> }
>>
>> /*
>> * Adjust to the fact that the hardware has an implicit "+1".
>> * NOTE: Above calculations always produce div_low > 0 and div_high > 0.
>> */
>> - *div_low = *div_low - 1;
>> - *div_high = *div_high - 1;
>> + t_output->div_low = t_output->div_low - 1;
> -= 1
>
>> + t_output->div_high = t_output->div_high - 1;
> Ditto.
>
> But without change of prototype those no needed.
>
>> /* Maximum divider supported by hw is 0xffff */
>> - if (*div_low > 0xffff) {
>> - *div_low = 0xffff;
>> + if (t_output->div_low > 0xffff) {
>> + t_output->div_low = 0xffff;
>> ret = -EINVAL;
>> }
>>
>> - if (*div_high > 0xffff) {
>> - *div_high = 0xffff;
>> + if (t_output->div_high > 0xffff) {
>> + t_output->div_high = 0xffff;
>> ret = -EINVAL;
>> }
>>
>> @@ -610,19 +632,21 @@ static int rk3x_i2c_calc_divs(unsigned long clk_rate,
>>
>> static void rk3x_i2c_adapt_div(struct rk3x_i2c *i2c, unsigned long clk_rate)
>> {
>> - unsigned long div_low, div_high;
>> u64 t_low_ns, t_high_ns;
>> int ret;
>>
>> - ret = rk3x_i2c_calc_divs(clk_rate, &i2c->t, &div_low, &div_high);
>> + ret = i2c->ops.calc_clock(clk_rate, &i2c->t, &i2c->t_priv);
>> WARN_ONCE(ret != 0, "Could not reach SCL freq %u", i2c->t.bus_freq_hz);
>>
>> clk_enable(i2c->clk);
>> - i2c_writel(i2c, (div_high << 16) | (div_low & 0xffff), REG_CLKDIV);
>> + i2c_writel(i2c, (i2c->t_priv.div_high << 16) |
>> + (i2c->t_priv.div_low & 0xffff), REG_CLKDIV);
>> clk_disable(i2c->clk);
>>
>> - t_low_ns = div_u64(((u64)div_low + 1) * 8 * 1000000000, clk_rate);
>> - t_high_ns = div_u64(((u64)div_high + 1) * 8 * 1000000000, clk_rate);
>> + t_low_ns = div_u64(((u64)i2c->t_priv.div_low + 1) * 8 * 1000000000,
>> + clk_rate);
>> + t_high_ns = div_u64(((u64)i2c->t_priv.div_high + 1) * 8 * 1000000000,
>> + clk_rate);
>> dev_dbg(i2c->dev,
>> "CLK %lukhz, Req %uns, Act low %lluns high %lluns\n",
>> clk_rate / 1000,
>> @@ -652,12 +676,11 @@ static int rk3x_i2c_clk_notifier_cb(struct notifier_block *nb, unsigned long
>> {
>> struct clk_notifier_data *ndata = data;
>> struct rk3x_i2c *i2c = container_of(nb, struct rk3x_i2c, clk_rate_nb);
>> - unsigned long div_low, div_high;
>>
>> switch (event) {
>> case PRE_RATE_CHANGE:
>> - if (rk3x_i2c_calc_divs(ndata->new_rate, &i2c->t,
>> - &div_low, &div_high) != 0)
>> + if (i2c->ops.calc_clock(ndata->new_rate, &i2c->t,
>> + &i2c->t_priv) != 0)
>> return NOTIFY_STOP;
>>
>> /* scale up */
>> @@ -861,6 +884,7 @@ static int rk3x_i2c_probe(struct platform_device *pdev)
>> u32 value;
>> int irq;
>> unsigned long clk_rate;
>> + unsigned int version;
> No need to have a separate variable…
>
>> + version = (readl(i2c->regs + REG_CON) & VERSION_MASK) >> VERSION_SHIFT;
>> + if (version == RK3X_I2C_V0)
>> + i2c->ops.calc_clock = rk3x_i2c_v0_calc_clock;
> value = readl(i2c->regs + REG_CON);
> if ((value & VERSION_MASK) >> VERSION_SHIFT) == RK3X_I2C_V0)
> i2c->ops.calc_clock = rk3x_i2c_v0_calc_clock;
>
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