[RFC 1/4] rtc: support for amlogic meson rtc
Ben Dooks
ben.dooks at codethink.co.uk
Fri Jun 24 07:54:12 PDT 2016
On 24/06/16 15:25, Neil Armstrong wrote:
> Hi Ben,
>
> On 06/23/2016 10:21 PM, Ben Dooks wrote:
>> Add support for the AMLogic meson8b/meson6 RTC block.
>>
>> Signed-off-by: Ben Dooks <ben.dooks at codethink.co.uk>
>> ---
>
> [...]
>
>> +
>> +/* registers accessed from cpu bus */
>> +#define RTC_REG(x) ((x) * 4) /* rtc registers 0-4 */
>> +
>> +#define LINE_SDI (1 << 2)
>> +#define LINE_SEN (1 << 1)
>> +#define LINE_SCLK (1 << 0)
>> +
>> +#define RTCREG0_START_SER BIT(17)
>> +#define RTCREG0_WAIT_SER BIT(22)
>> +
>> +#define RTCREG1_READY BIT(1)
>> +
>> +/* rtc registers accessed via rtc-serial inteface */
>> +#define RTC_COUNTER (0)
>> +#define RTC_SEC_ADJ (2)
>> +
>> +#define RTC_ADDR_BITS (3) /* number of address bits to send */
>> +#define RTC_DATA_BITS (32) /* number of data bits to tx/rx */
>> +
>> +#define MESON_STATIC_BIAS_CUR (0x5 << 1)
>> +#define MESON_STATIC_VOLTAGE (0x3 << 11)
>
> Cleanup indentation here.
ok, will do.
>> +
>> +struct meson_rtc {
>> + struct rtc_device *rtc; /* rtc device we created */
>> + struct device *dev; /* device we bound from */
>> + struct reset_control *reset; /* reset source */
>> + struct mutex lock; /* rtc lock */
>> + void __iomem *regs; /* rtc register access */
>> +};
>> +
>> +static void meson_rtc_setline(struct meson_rtc *rtc, unsigned bit, unsigned to)
>> +{
>> + u32 reg0;
>> +
>> + reg0 = readl(rtc->regs + RTC_REG(0));
>> + if (to)
>> + reg0 |= bit;
>> + else
>> + reg0 &= ~bit;
>> + writel(reg0, rtc->regs + RTC_REG(0));
>> +
>> +}
>> +
>> +static void meson_rtc_sclk_pulse(struct meson_rtc *rtc)
>> +{
>> + udelay(5);
>> + meson_rtc_setline(rtc, LINE_SCLK, 0);
>> + udelay(5);
>> + meson_rtc_setline(rtc, LINE_SCLK, 1);
>> +}
>> +
>> +static void meson_rtc_send_bit(struct meson_rtc *rtc, unsigned bit)
>> +{
>> + meson_rtc_setline(rtc, LINE_SDI, bit ? 1 : 0);
>
> You can use !!bit here also
I /could/ but I don't like it, and it's not going to improve the code.
>> + meson_rtc_sclk_pulse(rtc);
>> +}
>> +
>> +static void meson_rtc_send_bits(struct meson_rtc *rtc, u32 data, unsigned nr)
>> +{
>> + u32 bit = 1 << (nr - 1);
>> +
>> + while (bit) {
>> + meson_rtc_send_bit(rtc, data & bit);
>> + bit >>= 1;
>> + }
>> +}
>> +
>> +static void meson_rtc_set_dir(struct meson_rtc *rtc, u32 mode)
>> +{
>> + meson_rtc_setline(rtc, LINE_SDI, 0);
>> + meson_rtc_send_bit(rtc, mode);
>> + meson_rtc_setline(rtc, LINE_SDI, 0);
>> +}
>> +
>> +static u32 meson_rtc_read_sdo(struct meson_rtc *rtc)
>> +{
>> + return readl(rtc->regs + RTC_REG(1)) & (1 << 0);
>
> Drop the << 0 here, or replace by BIT(0)
ok, will do.
>> +}
>> +
>> +static u32 meson_rtc_get_data(struct meson_rtc *rtc)
>> +{
>> + u32 val = 0;
>> + int bit;
>> +
>> + for (bit = 0; bit < RTC_DATA_BITS; bit++) {
>> + meson_rtc_sclk_pulse(rtc);
>> + val <<= 1;
>> + val |= meson_rtc_read_sdo(rtc);
>> + }
>> +
>> + return val;
>> +}
>> +
>> +static int meson_rtc_wait_bus(struct meson_rtc *rtc, unsigned timeout_ms)
>> +{
>> + unsigned long timeout = jiffies + msecs_to_jiffies(timeout_ms);
>> + u32 val;
>> +
>> + val = readl(rtc->regs + RTC_REG(0));
>> + val &= ~(LINE_SDI | LINE_SEN | LINE_SCLK);
>> + writel(val, rtc->regs + RTC_REG(0));
>> +
>> + while (time_before(jiffies, timeout)) {
>> + val = readl(rtc->regs + RTC_REG(1));
>> + if (val & RTCREG1_READY)
>> + return 1;
>> +
>> + dev_info(rtc->dev, "%s: reg1=%08x\n", __func__, val);
>> + msleep(10);
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static int meson_rtc_get_bus(struct meson_rtc *rtc)
>> +{
>> + int ret, retries = 3;
>> +
>> + while (retries) {
>> + if (meson_rtc_wait_bus(rtc, 300))
>> + return 0;
>
> Put the timeout time in a define 300 to be easily changed.
not sure that's necessary, it's just in one place.
>> +
>> + dev_warn(rtc->dev, "failed to get bus, re-setting\n");
>> +
>> + retries--;
>> + ret = reset_control_reset(rtc->reset);
>> + if (ret)
>> + return ret;
>> + }
>> +
>> + dev_err(rtc->dev, "%s: bus is not ready\n", __func__);
>> + return -ETIMEDOUT;
>> +}
>> +
>> +static int meson_rtc_read(struct meson_rtc *rtc, unsigned int reg, u32 *data)
>> +{
>> + int ret;
>> +
>> + ret = meson_rtc_get_bus(rtc);
>> + if (ret)
>> + return ret;
>> +
>> + meson_rtc_setline(rtc, LINE_SEN, 1);
>> + meson_rtc_send_bits(rtc, reg, RTC_ADDR_BITS);
>> + meson_rtc_setline(rtc, LINE_SEN, 0);
>> + meson_rtc_set_dir(rtc, 0);
>> + *data = meson_rtc_get_data(rtc);
>> +
>> + return 0;
>> +}
>> +
>> +static int meson_rtc_write(struct meson_rtc *rtc, unsigned int reg, u32 data)
>> +{
>> + int ret;
>> +
>> + ret = meson_rtc_get_bus(rtc);
>> + if (ret)
>> + return ret;
>> +
>> + meson_rtc_setline(rtc, LINE_SEN, 1);
>> + meson_rtc_send_bits(rtc, reg, RTC_ADDR_BITS);
>> + meson_rtc_setline(rtc, LINE_SEN, 0);
>> + meson_rtc_set_dir(rtc, 1);
>> + meson_rtc_send_bits(rtc, data, RTC_DATA_BITS);
>> +
>> + return 0;
>> +}
>> +
>> +static int meson_rtc_gettime(struct device *dev, struct rtc_time *tm)
>> +{
>> + struct meson_rtc *rtc = dev_get_drvdata(dev);
>> + int ret;
>> + u32 time;
>> +
>> + mutex_lock(&rtc->lock);
>> +
>> + ret = meson_rtc_read(rtc, RTC_COUNTER, &time);
>> + if (ret)
>> + return ret;
>> +
>> + rtc_time_to_tm(time, tm);
>> + dev_info(dev, "read time %lu\n", (unsigned long)time);
>
> Replace by a dev_dbg here.
Already done for v2.
>> +
>> + mutex_unlock(&rtc->lock);
>> + return 0;
>> +}
>> +
>> +static int meson_rtc_settime(struct device *dev, struct rtc_time *tm)
>> +{
>> + struct meson_rtc *rtc = dev_get_drvdata(dev);
>> + unsigned long time;
>> + int ret;
>> +
>> + mutex_lock(&rtc->lock);
>> +
>> + rtc_tm_to_time(tm, &time);
>> + ret = meson_rtc_write(rtc, RTC_COUNTER, time);
>> +
>> + mutex_unlock(&rtc->lock);
>> + return ret;
>> +}
>> +
>> +static const struct rtc_class_ops meson_rtc_ops = {
>> + .read_time = meson_rtc_gettime,
>> + .set_time = meson_rtc_settime,
>> +};
>> +
>> +static int meson_rtc_wait_serialiser(struct meson_rtc *rtc)
>> +{
>> + unsigned long timeout = jiffies + msecs_to_jiffies(100);
>> +
>> + while (time_before(jiffies, timeout)) {
>> + if (!(readl(rtc->regs + RTC_REG(0)) & RTCREG0_WAIT_SER))
>> + return 0;
>> + msleep(10);
>> + }
>> +
>> + return -ETIMEDOUT;
>> +}
>> +
>> +static int meson_rtc_write_static(struct meson_rtc *rtc, u32 data)
>> +{
>> + u32 tmp;
>> +
>> + mutex_lock(&rtc->lock);
>> +
>> + writel(data >> 8, rtc->regs + RTC_REG(4));
>> +
>> + tmp = readl(rtc->regs + RTC_REG(0));
>> + tmp &= ~(0xff << 24);
>> + tmp |= (data << 24);
>> + tmp |= RTCREG0_START_SER;
>
> Add a define for the shifts here.
>
>> +
>> + writel(tmp, rtc->regs + RTC_REG(0));
>> +
>> + if (meson_rtc_wait_serialiser(rtc))
>> + return -ETIMEDOUT;
>> +
>> + dev_info(rtc->dev, "rtc_reg0 = %08x\n", readl(rtc->regs + RTC_REG(0)));
>> + mutex_unlock(&rtc->lock);
>> +
>
> dev_dbg instead here.
Yep, caught already for v2.
>> + return 0;
>> +}
>> +
>> +static int meson_rtc_probe(struct platform_device *pdev)
>> +{
>> + struct meson_rtc *rtc;
>> + struct device *dev = &pdev->dev;
>> + struct resource *res;
>> + u32 tm;
>> + int ret;
>> +
>> + rtc = devm_kzalloc(dev, sizeof(struct meson_rtc), GFP_KERNEL);
>> + if (!rtc) {
>> + dev_err(dev, "failed to allocate memory\n");
>> + return -ENOMEM;
>> + }
>> +
>> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> + rtc->regs = devm_ioremap_resource(dev, res);
>> + rtc->dev = dev;
>> +
>> + if (IS_ERR(rtc->regs))
>> + return PTR_ERR(rtc->regs);
>> +
>> + mutex_init(&rtc->lock);
>> + platform_set_drvdata(pdev, rtc);
>> +
>> + ret = meson_rtc_write_static(rtc,
>> + MESON_STATIC_BIAS_CUR | MESON_STATIC_VOLTAGE);
>> + if (ret) {
>> + dev_err(dev, "failed to set static values\n");
>> + return ret;
>> + }
>> +
>> + rtc->reset = devm_reset_control_get(dev, NULL);
>> + if (IS_ERR(rtc->reset))
>> + dev_warn(dev, "no reset available, rtc may not work\n");
>> +
>> + /* check if we can read RTC counter, if not then the RTC is probably
>> + * not functional. If it isn't probably best to not bind */
>> + ret = meson_rtc_read(rtc, RTC_COUNTER, &tm);
>> + if (ret) {
>> + dev_err(dev, "cannot read RTC counter, RTC not functional\n");
>> + return ret;
>> + }
>> +
>> + rtc->rtc = devm_rtc_device_register(dev, "meson",
>> + &meson_rtc_ops, THIS_MODULE);
>> + if (IS_ERR(rtc->rtc)) {
>> + dev_err(dev, "cannot attach rtc\n");
>> + return PTR_ERR(rtc->rtc);
>> + }
>> +
>> + dev_info(dev, "device registered\n");
>> + return 0;
>> +}
>> +
>> +static const struct of_device_id meson_rtc_dt_match[] = {
>> + { .compatible = "amlogic,meson6-rtc", },
>> + { .compatible = "amlogic,meson8-rtc", },
>> + { .compatible = "amlogic,meson8b-rtc", },
>> + { },
>> +};
>> +MODULE_DEVICE_TABLE(of, meson_rtc_dt_match);
>> +
>> +static struct platform_driver meson_rtc_driver = {
>> + .probe = meson_rtc_probe,
>> + .driver = {
>> + .name = "meson-rtc",
>> + .of_match_table = of_match_ptr(meson_rtc_dt_match),
>> + },
>> +};
>> +module_platform_driver(meson_rtc_driver);
>> +
>> +MODULE_DESCRIPTION("AMLogic MESON RTC Driver");
>> +MODULE_AUTHOR("Ben Dooks <ben.doosk at codethink.co.uk>");
>> +MODULE_LICENSE("GPL");
>> +MODULE_ALIAS("platform:meson-rtc");
>>
>
>
> Neil
Ta.
--
Ben Dooks http://www.codethink.co.uk/
Senior Engineer Codethink - Providing Genius
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