[PATCH v5] rtc: support DS1302 RTC on ICP DAS LP-8x4x

[PATCH v5] rtc: support DS1302 RTC on ICP DAS LP-8x4x

[Sergei Ianovich]

Signed-off-by: Sergei Ianovich <ynvich@gmail.com>
CC: Alexandre Belloni <alexandre.belloni@free-electrons.com>
---
   v4..v5
   * drop THIS_MODULE from struct platform driver
   * use "dallas" for vendor name per vendor-prefixes.txt

   v3..v4
   * move DTS bindings to a different patch

   v2..v3
   * use usleep_range instead of custom nsleep
   * number change (07/16 -> 09/21)

   v0..v2
   * use device tree
   * use devm helpers where possible

 .../devicetree/bindings/rtc/rtc-ds1302.txt         |  14 +++
 drivers/rtc/Kconfig                                |   2 +-
 drivers/rtc/rtc-ds1302.c                           | 100 ++++++++++++++++++++-
 3 files changed, 113 insertions(+), 3 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/rtc/rtc-ds1302.txt

diff --git a/Documentation/devicetree/bindings/rtc/rtc-ds1302.txt b/Documentation/devicetree/bindings/rtc/rtc-ds1302.txt
new file mode 100644
index 0000000..810613b
--- /dev/null
+++ b/Documentation/devicetree/bindings/rtc/rtc-ds1302.txt
@@ -0,0 +1,14 @@
+* Dallas Semiconductor DS-1302 RTC
+
+Simple device which could be used to store date/time between reboots.
+
+Required properties:
+- compatible : Should be "dallas,rtc-ds1302"
+- reg : Should be address and size of IO memory region
+
+Examples:
+
+rtc@40900000 {
+	compatible = "dallas,rtc-ds1302";
+	reg = <0x1700901c 0x1>;
+};
diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 2a52424..cf36483 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -803,7 +803,7 @@ config RTC_DRV_DS1286
 
 config RTC_DRV_DS1302
 	tristate "Dallas DS1302"
-	depends on SH_SECUREEDGE5410
+	depends on SH_SECUREEDGE5410 || (ARCH_PXA && HIGH_RES_TIMERS)
 	help
 	  If you say yes here you get support for the Dallas DS1302 RTC chips.
 
diff --git a/drivers/rtc/rtc-ds1302.c b/drivers/rtc/rtc-ds1302.c
index 6bef7a5..bd68214 100644
--- a/drivers/rtc/rtc-ds1302.c
+++ b/drivers/rtc/rtc-ds1302.c
@@ -50,7 +50,7 @@
 #define ds1302_set_tx()
 #define ds1302_set_rx()
 
-static inline int ds1302_hw_init(void)
+static inline int ds1302_hw_init(struct platform_device *pdev)
 {
 	return 0;
 }
@@ -86,6 +86,101 @@ static inline int ds1302_rxbit(void)
 	return !!(get_dp() & RTC_IODATA);
 }
 
+#elif defined(CONFIG_ARCH_PXA) && defined(CONFIG_HIGH_RES_TIMERS)
+
+#include <linux/delay.h>
+#include <linux/of.h>
+
+#define	RTC_CE		0x01
+#define	RTC_CLK		0x02
+#define	RTC_nWE		0x04
+#define	RTC_IODATA	0x08
+
+static unsigned long ds1302_state;
+
+static void *mem;
+
+static inline int ds1302_hw_init(struct platform_device *pdev)
+{
+	struct resource *r;
+
+	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!r)
+		return -ENODEV;
+
+	mem = devm_ioremap_resource(&pdev->dev, r);
+	if (!mem)
+		return -EFAULT;
+
+	return 0;
+}
+
+static inline void ds1302_reset(void)
+{
+	ds1302_state = 0;
+	iowrite8(ds1302_state, mem);
+	usleep_range(4, 5);
+}
+
+static inline void ds1302_clock(void)
+{
+	usleep_range(1, 2);
+	ds1302_state |= RTC_CLK;
+	iowrite8(ds1302_state, mem);
+	usleep_range(1, 2);
+	ds1302_state &= ~RTC_CLK;
+	iowrite8(ds1302_state, mem);
+}
+
+static inline void ds1302_start(void)
+{
+	ds1302_state &= ~RTC_CLK;
+	ds1302_state |= RTC_CE;
+	iowrite8(ds1302_state, mem);
+	usleep_range(3, 4);
+}
+
+static inline void ds1302_stop(void)
+{
+	ds1302_state &= ~RTC_CE;
+	iowrite8(ds1302_state, mem);
+}
+
+static inline void ds1302_set_tx(void)
+{
+	ds1302_state &= ~RTC_nWE;
+	iowrite8(ds1302_state, mem);
+}
+
+static inline void ds1302_set_rx(void)
+{
+	ds1302_state |= RTC_nWE;
+	iowrite8(ds1302_state, mem);
+}
+
+static inline void ds1302_txbit(int bit)
+{
+	if (bit)
+		ds1302_state |= RTC_IODATA;
+	else
+		ds1302_state &= ~RTC_IODATA;
+	iowrite8(ds1302_state, mem);
+}
+
+static inline int ds1302_rxbit(void)
+{
+	return ioread8(mem) & 0x1;
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id ds1302_dt_ids[] = {
+	{ .compatible = "dallas,rtc-ds1302" },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(of, ds1302_dt_ids);
+#endif
+
 #else
 #error "Add support for your platform"
 #endif
@@ -216,7 +311,7 @@ static int __init ds1302_rtc_probe(struct platform_device *pdev)
 {
 	struct rtc_device *rtc;
 
-	if (ds1302_hw_init()) {
+	if (ds1302_hw_init(pdev)) {
 		dev_err(&pdev->dev, "Failed to init communication channel");
 		return -EINVAL;
 	}
@@ -244,6 +339,7 @@ static int __init ds1302_rtc_probe(struct platform_device *pdev)
 static struct platform_driver ds1302_platform_driver = {
 	.driver		= {
 		.name	= DRV_NAME,
+		.of_match_table = of_match_ptr(ds1302_dt_ids),
 	},
 };
 
-- 
2.6.2

Re: [PATCH v5] rtc: support DS1302 RTC on ICP DAS LP-8x4x

[Rob Herring]

On Tue, Dec 15, 2015 at 08:45:23PM +0300, Sergei Ianovich wrote:

Nothing in this is specific to ICP, so the subject should be updated.

> Signed-off-by: Sergei Ianovich <ynvich@gmail.com>
> CC: Alexandre Belloni <alexandre.belloni@free-electrons.com>
> ---
>    v4..v5
>    * drop THIS_MODULE from struct platform driver
>    * use "dallas" for vendor name per vendor-prefixes.txt
> 
>    v3..v4
>    * move DTS bindings to a different patch
> 
>    v2..v3
>    * use usleep_range instead of custom nsleep
>    * number change (07/16 -> 09/21)
> 
>    v0..v2
>    * use device tree
>    * use devm helpers where possible
> 
>  .../devicetree/bindings/rtc/rtc-ds1302.txt         |  14 +++
>  drivers/rtc/Kconfig                                |   2 +-
>  drivers/rtc/rtc-ds1302.c                           | 100 ++++++++++++++++++++-
>  3 files changed, 113 insertions(+), 3 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/rtc/rtc-ds1302.txt
> 
> diff --git a/Documentation/devicetree/bindings/rtc/rtc-ds1302.txt b/Documentation/devicetree/bindings/rtc/rtc-ds1302.txt
> new file mode 100644
> index 0000000..810613b
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/rtc/rtc-ds1302.txt
> @@ -0,0 +1,14 @@
> +* Dallas Semiconductor DS-1302 RTC
> +
> +Simple device which could be used to store date/time between reboots.
> +
> +Required properties:
> +- compatible : Should be "dallas,rtc-ds1302"
> +- reg : Should be address and size of IO memory region

This device is a SPI (or SPI like?) interface. So you have some sort of 
of FPGA logic in between the cpu and ds1302. The DT should have a node 
for the controller and then the ds1302 as a child of it. A full blown 
SPI driver may be overkill here, but that's a separate discussion from 
the DT binding.

Rob

> +
> +Examples:
> +
> +rtc@40900000 {
> +	compatible = "dallas,rtc-ds1302";
> +	reg = <0x1700901c 0x1>;
> +};

Re: [PATCH v5] rtc: support DS1302 RTC on ICP DAS LP-8x4x

[Sergei Ianovich]

On Sat, 2015-12-19 at 21:38 -0600, Rob Herring wrote:
> On Tue, Dec 15, 2015 at 08:45:23PM +0300, Sergei Ianovich wrote:
> 
> Nothing in this is specific to ICP, so the subject should be updated.
> 
> > Signed-off-by: Sergei Ianovich <ynvich@gmail.com>
> > CC: Alexandre Belloni <alexandre.belloni@free-electrons.com>
> > ---
> >    v4..v5
> >    * drop THIS_MODULE from struct platform driver
> >    * use "dallas" for vendor name per vendor-prefixes.txt
> > 
> >    v3..v4
> >    * move DTS bindings to a different patch
> > 
> >    v2..v3
> >    * use usleep_range instead of custom nsleep
> >    * number change (07/16 -> 09/21)
> > 
> >    v0..v2
> >    * use device tree
> >    * use devm helpers where possible
> > 
> >  .../devicetree/bindings/rtc/rtc-ds1302.txt         |  14 +++
> >  drivers/rtc/Kconfig                                |   2 +-
> >  drivers/rtc/rtc-ds1302.c                           | 100
> > ++++++++++++++++++++-
> >  3 files changed, 113 insertions(+), 3 deletions(-)
> >  create mode 100644 Documentation/devicetree/bindings/rtc/rtc-
> > ds1302.txt
> > 
> > diff --git a/Documentation/devicetree/bindings/rtc/rtc-ds1302.txt
> > b/Documentation/devicetree/bindings/rtc/rtc-ds1302.txt
> > new file mode 100644
> > index 0000000..810613b
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/rtc/rtc-ds1302.txt
> > @@ -0,0 +1,14 @@
> > +* Dallas Semiconductor DS-1302 RTC
> > +
> > +Simple device which could be used to store date/time between
> > reboots.
> > +
> > +Required properties:
> > +- compatible : Should be "dallas,rtc-ds1302"
> > +- reg : Should be address and size of IO memory region
> 
> This device is a SPI (or SPI like?) interface. So you have some sort
> of 
> of FPGA logic in between the cpu and ds1302. The DT should have a node
> for the controller and then the ds1302 as a child of it. A full blown 
> SPI driver may be overkill here, but that's a separate discussion from
> the DT binding.

Below is the quote from the actual DT of LP-8x4x:
>                 fpga@5 {
>                         compatible = "simple-bus";
>                         #address-cells = <1>;
>                         #size-cells = <1>;
>                         ranges = <0 5 0x3000000 0x10000>;
>                         interrupt-parent = <&fpgairq>;
> 
>                         rtc@901c {
>                                 compatible = "dallas,rtc-ds1302";
>                                 reg = <0x901c 0x1>;
>                                 status = "okay";
>                         };

You are right about the topology. ds1302 is a half-duplex SPI device.
Does this mean I should rewrite the driver to handle the chip as a slave
SPI device, and then provide a master SPI functionality at the FPGA?

Re: [PATCH v5] rtc: support DS1302 RTC on ICP DAS LP-8x4x

[Rob Herring]

On Sun, Dec 20, 2015 at 6:14 AM, Sergei Ianovich <ynvich@gmail.com> wrote:
> On Sat, 2015-12-19 at 21:38 -0600, Rob Herring wrote:
>> On Tue, Dec 15, 2015 at 08:45:23PM +0300, Sergei Ianovich wrote:

[...]

>> > diff --git a/Documentation/devicetree/bindings/rtc/rtc-ds1302.txt
>> > b/Documentation/devicetree/bindings/rtc/rtc-ds1302.txt
>> > new file mode 100644
>> > index 0000000..810613b
>> > --- /dev/null
>> > +++ b/Documentation/devicetree/bindings/rtc/rtc-ds1302.txt
>> > @@ -0,0 +1,14 @@
>> > +* Dallas Semiconductor DS-1302 RTC
>> > +
>> > +Simple device which could be used to store date/time between
>> > reboots.
>> > +
>> > +Required properties:
>> > +- compatible : Should be "dallas,rtc-ds1302"
>> > +- reg : Should be address and size of IO memory region
>>
>> This device is a SPI (or SPI like?) interface. So you have some sort
>> of
>> of FPGA logic in between the cpu and ds1302. The DT should have a node
>> for the controller and then the ds1302 as a child of it. A full blown
>> SPI driver may be overkill here, but that's a separate discussion from
>> the DT binding.
>
> Below is the quote from the actual DT of LP-8x4x:
>>                 fpga@5 {
>>                         compatible = "simple-bus";
>>                         #address-cells = <1>;
>>                         #size-cells = <1>;
>>                         ranges = <0 5 0x3000000 0x10000>;
>>                         interrupt-parent = <&fpgairq>;
>>
>>                         rtc@901c {
>>                                 compatible = "dallas,rtc-ds1302";

This node should have a LP-8x4x specific compatible and then have a
child node for ds1302 that follows the SPI binding.

>>                                 reg = <0x901c 0x1>;
>>                                 status = "okay";
>>                         };
>
> You are right about the topology. ds1302 is a half-duplex SPI device.
> Does this mean I should rewrite the driver to handle the chip as a slave
> SPI device, and then provide a master SPI functionality at the FPGA?

Well, the binding should reflect that, whether the driver needs to be
re-written is somewhat a separate question. That should probably have
been done for the DS1302 driver originally and it is not too fair for
the 2nd person to fix it. You could just have a single driver bound to
the controller node which is aware of the DS1302 being the slave
device (ignoring that part of the DT for now).

Rob

Re: [PATCH v5] rtc: support DS1302 RTC on ICP DAS LP-8x4x

[Alexandre Belloni]

Hi,

On 22/12/2015 at 12:16:41 -0600, Rob Herring wrote :
> Well, the binding should reflect that, whether the driver needs to be
> re-written is somewhat a separate question. That should probably have
> been done for the DS1302 driver originally and it is not too fair for
> the 2nd person to fix it. You could just have a single driver bound to
> the controller node which is aware of the DS1302 being the slave
> device (ignoring that part of the DT for now).
> 

I agree with Rob here. I won't require that you fix the driver but it
would be better to have a proper DT binding from the beginning so that
when the driver is fixed it will still work with the previous device
trees.

-- 
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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Re: [PATCH v5] rtc: support DS1302 RTC on ICP DAS LP-8x4x

[Sergei Ianovich]

On Thu, 2015-12-24 at 12:04 +0100, Alexandre Belloni wrote:
> On 22/12/2015 at 12:16:41 -0600, Rob Herring wrote :
> > Well, the binding should reflect that, whether the driver needs to
> > be
> > re-written is somewhat a separate question. That should probably
> > have
> > been done for the DS1302 driver originally and it is not too fair
> > for
> > the 2nd person to fix it. You could just have a single driver bound
> > to
> > the controller node which is aware of the DS1302 being the slave
> > device (ignoring that part of the DT for now).
> > 
> 
> I agree with Rob here. I won't require that you fix the driver but it
> would be better to have a proper DT binding from the beginning so that
> when the driver is fixed it will still work with the previous device
> trees.

No problem. I'll fix the driver. That's how it should be done.

What should be done with SECUREEDGE support?

[PATCH v6] rtc: rewrite DS1302 using SPI

[Sergei Ianovich]

DS1302 is half-duplex SPI device. The driver respects this fact now.

Pin configurations should be implemented using SPI subsystem.

Signed-off-by: Sergei Ianovich <ynvich@gmail.com>
CC: Alexandre Belloni <alexandre.belloni@free-electrons.com>
CC: Rob Herring <robh@kernel.org>
---
   v5..v6
   * rewrite the driver as an SPI slave device
   * use "maxim" for vendor name per Kconfig
   * stop touching device RAM in device presence test
   * only return time from device if valid
   * use burst mode for reading/writing time
   * droppped charging control. I cannot test it, and it looks broken

   v4..v5
   * drop THIS_MODULE from struct platform driver
   * use "dallas" for vendor name per vendor-prefixes.txt

   v3..v4
   * move DTS bindings to a different patch

   v2..v3
   * use usleep_range instead of custom nsleep
   * number change (07/16 -> 09/21)

   v0..v2
   * use device tree
   * use devm helpers where possible

 .../devicetree/bindings/rtc/rtc-ds1302.txt         |  46 +++
 drivers/rtc/Kconfig                                |  15 +-
 drivers/rtc/rtc-ds1302.c                           | 348 ++++++++++-----------
 3 files changed, 212 insertions(+), 197 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/rtc/rtc-ds1302.txt

diff --git a/Documentation/devicetree/bindings/rtc/rtc-ds1302.txt b/Documentation/devicetree/bindings/rtc/rtc-ds1302.txt
new file mode 100644
index 0000000..b6c0973
--- /dev/null
+++ b/Documentation/devicetree/bindings/rtc/rtc-ds1302.txt
@@ -0,0 +1,46 @@
+* Maxim/Dallas Semiconductor DS-1302 RTC
+
+Simple device which could be used to store date/time between reboots.
+
+The device uses the standard MicroWire half-duplex transfer timing.
+Master output is set on low clock and sensed by the RTC on the rising
+edge. Master input is set by the RTC on the trailing edge and is sensed
+by the master on low clock.
+
+Required properties:
+
+- compatible : Should be "maxim,rtc-ds1302"
+
+Required SPI properties:
+
+- reg : Should be address of the device chip select within
+  the controller.
+
+- spi-max-frequency : DS-1302 has 500 kHz if powered at 2.2V,
+  and 2MHz if powered at 5V.
+
+- spi-3wire : The device has a shared signal IN/OUT line.
+
+- spi-lsb-first : DS-1302 requires least significant bit first
+  transfers.
+
+- spi-cs-high: DS-1302 has active high chip select line. This is
+  required unless inverted in hardware.
+
+Example:
+
+spi0@901c {
+	#address-cells = <1>;
+	#size-cells = <0>;
+	compatible = "icpdas,spi-lp8841-rtc";
+	reg = <0x901c 0x1>;
+
+	rtc@0 {
+		compatible = "maxim,rtc-ds1302";
+		reg = <0>;
+		spi-max-frequency = <500000>;
+		spi-3wire;
+		spi-lsb-first;
+		spi-cs-high;
+	};
+};
diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 2a52424..2e54aad 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -646,6 +646,15 @@ config RTC_DRV_M41T94
 	  This driver can also be built as a module. If so, the module
 	  will be called rtc-m41t94.
 
+config RTC_DRV_DS1302
+	tristate "Dallas/Maxim DS1302"
+	depends on SPI
+	help
+	  If you say yes here you get support for the Dallas DS1302 RTC chips.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called rtc-ds1302.
+
 config RTC_DRV_DS1305
 	tristate "Dallas/Maxim DS1305/DS1306"
 	help
@@ -811,12 +820,6 @@ config RTC_DRV_DS1286
 	help
 	  If you say yes here you get support for the Dallas DS1286 RTC chips.
 
-config RTC_DRV_DS1302
-	tristate "Dallas DS1302"
-	depends on SH_SECUREEDGE5410
-	help
-	  If you say yes here you get support for the Dallas DS1302 RTC chips.
-
 config RTC_DRV_DS1511
 	tristate "Dallas DS1511"
 	depends on HAS_IOMEM
diff --git a/drivers/rtc/rtc-ds1302.c b/drivers/rtc/rtc-ds1302.c
index 6bef7a5..89a210b 100644
--- a/drivers/rtc/rtc-ds1302.c
+++ b/drivers/rtc/rtc-ds1302.c
@@ -9,16 +9,17 @@
  * this archive for more details.
  */
 
+#include <linux/bcd.h>
 #include <linux/init.h>
-#include <linux/module.h>
+#include <linux/io.h>
 #include <linux/kernel.h>
-#include <linux/platform_device.h>
+#include <linux/module.h>
+#include <linux/of.h>
 #include <linux/rtc.h>
-#include <linux/io.h>
-#include <linux/bcd.h>
+#include <linux/spi/spi.h>
 
 #define DRV_NAME	"rtc-ds1302"
-#define DRV_VERSION	"0.1.1"
+#define DRV_VERSION	"1.0.0"
 
 #define	RTC_CMD_READ	0x81		/* Read command */
 #define	RTC_CMD_WRITE	0x80		/* Write command */
@@ -28,6 +29,8 @@
 
 #define RTC_ADDR_RAM0	0x20		/* Address of RAM0 */
 #define RTC_ADDR_TCR	0x08		/* Address of trickle charge register */
+#define RTC_CLCK_BURST	0x1F		/* Address of clock burst */
+#define	RTC_CLCK_LEN	0x08		/* Size of clock burst */
 #define	RTC_ADDR_CTRL	0x07		/* Address of control register */
 #define	RTC_ADDR_YEAR	0x06		/* Address of year register */
 #define	RTC_ADDR_DAY	0x05		/* Address of day of week register */
@@ -37,217 +40,180 @@
 #define	RTC_ADDR_MIN	0x01		/* Address of minute register */
 #define	RTC_ADDR_SEC	0x00		/* Address of second register */
 
-#ifdef CONFIG_SH_SECUREEDGE5410
-#include <asm/rtc.h>
-#include <mach/secureedge5410.h>
-
-#define	RTC_RESET	0x1000
-#define	RTC_IODATA	0x0800
-#define	RTC_SCLK	0x0400
-
-#define set_dp(x)	SECUREEDGE_WRITE_IOPORT(x, 0x1c00)
-#define get_dp()	SECUREEDGE_READ_IOPORT()
-#define ds1302_set_tx()
-#define ds1302_set_rx()
-
-static inline int ds1302_hw_init(void)
+static int ds1302_rtc_set_time(struct device *dev, struct rtc_time *time)
 {
-	return 0;
+	struct spi_device	*spi = dev_get_drvdata(dev);
+	u8		buf[1 + RTC_CLCK_LEN];
+	u8		*bp = buf;
+	int		status;
+
+	/* Enable writing */
+	bp = buf;
+	*bp++ = RTC_ADDR_CTRL << 1 | RTC_CMD_WRITE;
+	*bp++ = RTC_CMD_WRITE_ENABLE;
+
+	status = spi_write_then_read(spi, buf, 2,
+			NULL, 0);
+	if (!status)
+		return status;
+
+	/* Write registers starting at the first time/date address. */
+	bp = buf;
+	*bp++ = RTC_CLCK_BURST << 1 | RTC_CMD_WRITE;
+
+	*bp++ = bin2bcd(time->tm_sec);
+	*bp++ = bin2bcd(time->tm_min);
+	*bp++ = bin2bcd(time->tm_hour);
+	*bp++ = bin2bcd(time->tm_mday);
+	*bp++ = bin2bcd(time->tm_mon + 1);
+	*bp++ = time->tm_wday;
+	*bp++ = bin2bcd(time->tm_year % 100);
+	*bp++ = RTC_CMD_WRITE_DISABLE;
+
+	/* use write-then-read since dma from stack is nonportable */
+	return spi_write_then_read(spi, buf, sizeof(buf),
+			NULL, 0);
 }
 
-static inline void ds1302_reset(void)
+static int ds1302_rtc_get_time(struct device *dev, struct rtc_time *time)
 {
-	set_dp(get_dp() & ~(RTC_RESET | RTC_IODATA | RTC_SCLK));
+	struct spi_device	*spi = dev_get_drvdata(dev);
+	u8		addr = RTC_CLCK_BURST << 1 | RTC_CMD_READ;
+	u8		buf[RTC_CLCK_LEN - 1];
+	int		status;
+
+	/* Use write-then-read to get all the date/time registers
+	 * since dma from stack is nonportable
+	 */
+	status = spi_write_then_read(spi, &addr, sizeof(addr),
+			buf, sizeof(buf));
+	if (status < 0)
+		return status;
+
+	/* Decode the registers */
+	time->tm_sec = bcd2bin(buf[RTC_ADDR_SEC]);
+	time->tm_min = bcd2bin(buf[RTC_ADDR_MIN]);
+	time->tm_hour = bcd2bin(buf[RTC_ADDR_HOUR]);
+	time->tm_wday = buf[RTC_ADDR_DAY] - 1;
+	time->tm_mday = bcd2bin(buf[RTC_ADDR_DATE]);
+	time->tm_mon = bcd2bin(buf[RTC_ADDR_MON]) - 1;
+	time->tm_year = bcd2bin(buf[RTC_ADDR_YEAR]) + 100;
+
+	/* Time may not be set */
+	return rtc_valid_tm(time);
 }
 
-static inline void ds1302_clock(void)
-{
-	set_dp(get_dp() | RTC_SCLK);	/* clock high */
-	set_dp(get_dp() & ~RTC_SCLK);	/* clock low */
-}
-
-static inline void ds1302_start(void)
-{
-	set_dp(get_dp() | RTC_RESET);
-}
-
-static inline void ds1302_stop(void)
-{
-	set_dp(get_dp() & ~RTC_RESET);
-}
-
-static inline void ds1302_txbit(int bit)
-{
-	set_dp((get_dp() & ~RTC_IODATA) | (bit ? RTC_IODATA : 0));
-}
-
-static inline int ds1302_rxbit(void)
-{
-	return !!(get_dp() & RTC_IODATA);
-}
-
-#else
-#error "Add support for your platform"
-#endif
+static struct rtc_class_ops ds1302_rtc_ops = {
+	.read_time	= ds1302_rtc_get_time,
+	.set_time	= ds1302_rtc_set_time,
+};
 
-static void ds1302_sendbits(unsigned int val)
+static int ds1302_probe(struct spi_device *spi)
 {
-	int i;
-
-	ds1302_set_tx();
-
-	for (i = 8; (i); i--, val >>= 1) {
-		ds1302_txbit(val & 0x1);
-		ds1302_clock();
+	struct rtc_device	*rtc;
+	u8		addr;
+	u8		buf[4];
+	u8		*bp = buf;
+	int		status;
+
+	/* Sanity check board setup data.  This may be hooked up
+	 * in 3wire mode, but we don't care.  Note that unless
+	 * there's an inverter in place, this needs SPI_CS_HIGH!
+	 */
+	if (spi->bits_per_word && (spi->bits_per_word != 8)) {
+		dev_err(&spi->dev, "bad word length\n");
+		return -EINVAL;
+	} else if (spi->max_speed_hz > 2000000) {
+		dev_err(&spi->dev, "speed is too high\n");
+		return -EINVAL;
+	} else if (spi->mode & SPI_CPHA) {
+		dev_err(&spi->dev, "bad mode\n");
+		return -EINVAL;
 	}
-}
-
-static unsigned int ds1302_recvbits(void)
-{
-	unsigned int val;
-	int i;
-
-	ds1302_set_rx();
 
-	for (i = 0, val = 0; (i < 8); i++) {
-		val |= (ds1302_rxbit() << i);
-		ds1302_clock();
+	addr = RTC_ADDR_CTRL << 1 | RTC_CMD_READ;
+	status = spi_write_then_read(spi, &addr, sizeof(addr), buf, 1);
+	if (status < 0) {
+		dev_err(&spi->dev, "control register read error %d\n",
+				status);
+		return status;
 	}
 
-	return val;
-}
-
-static unsigned int ds1302_readbyte(unsigned int addr)
-{
-	unsigned int val;
-
-	ds1302_reset();
-
-	ds1302_start();
-	ds1302_sendbits(((addr & 0x3f) << 1) | RTC_CMD_READ);
-	val = ds1302_recvbits();
-	ds1302_stop();
-
-	return val;
-}
-
-static void ds1302_writebyte(unsigned int addr, unsigned int val)
-{
-	ds1302_reset();
-
-	ds1302_start();
-	ds1302_sendbits(((addr & 0x3f) << 1) | RTC_CMD_WRITE);
-	ds1302_sendbits(val);
-	ds1302_stop();
-}
-
-static int ds1302_rtc_read_time(struct device *dev, struct rtc_time *tm)
-{
-	tm->tm_sec	= bcd2bin(ds1302_readbyte(RTC_ADDR_SEC));
-	tm->tm_min	= bcd2bin(ds1302_readbyte(RTC_ADDR_MIN));
-	tm->tm_hour	= bcd2bin(ds1302_readbyte(RTC_ADDR_HOUR));
-	tm->tm_wday	= bcd2bin(ds1302_readbyte(RTC_ADDR_DAY));
-	tm->tm_mday	= bcd2bin(ds1302_readbyte(RTC_ADDR_DATE));
-	tm->tm_mon	= bcd2bin(ds1302_readbyte(RTC_ADDR_MON)) - 1;
-	tm->tm_year	= bcd2bin(ds1302_readbyte(RTC_ADDR_YEAR));
-
-	if (tm->tm_year < 70)
-		tm->tm_year += 100;
-
-	dev_dbg(dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
-		"mday=%d, mon=%d, year=%d, wday=%d\n",
-		__func__,
-		tm->tm_sec, tm->tm_min, tm->tm_hour,
-		tm->tm_mday, tm->tm_mon + 1, tm->tm_year, tm->tm_wday);
-
-	return rtc_valid_tm(tm);
-}
-
-static int ds1302_rtc_set_time(struct device *dev, struct rtc_time *tm)
-{
-	ds1302_writebyte(RTC_ADDR_CTRL, RTC_CMD_WRITE_ENABLE);
-	/* Stop RTC */
-	ds1302_writebyte(RTC_ADDR_SEC, ds1302_readbyte(RTC_ADDR_SEC) | 0x80);
-
-	ds1302_writebyte(RTC_ADDR_SEC, bin2bcd(tm->tm_sec));
-	ds1302_writebyte(RTC_ADDR_MIN, bin2bcd(tm->tm_min));
-	ds1302_writebyte(RTC_ADDR_HOUR, bin2bcd(tm->tm_hour));
-	ds1302_writebyte(RTC_ADDR_DAY, bin2bcd(tm->tm_wday));
-	ds1302_writebyte(RTC_ADDR_DATE, bin2bcd(tm->tm_mday));
-	ds1302_writebyte(RTC_ADDR_MON, bin2bcd(tm->tm_mon + 1));
-	ds1302_writebyte(RTC_ADDR_YEAR, bin2bcd(tm->tm_year % 100));
+	if ((buf[0] & ~RTC_CMD_WRITE_DISABLE) != 0) {
+		status = spi_write_then_read(spi, &addr, sizeof(addr), buf, 1);
+		if (status < 0) {
+			dev_err(&spi->dev, "control register read error %d\n",
+					status);
+			return status;
+		}
+
+		if ((buf[0] & ~RTC_CMD_WRITE_DISABLE) != 0) {
+			dev_err(&spi->dev, "junk in control register\n");
+			return -ENODEV;
+		}
+	}
+	if (buf[0] == 0) {
+		bp = buf;
+		*bp++ = RTC_ADDR_CTRL << 1 | RTC_CMD_WRITE;
+		*bp++ = RTC_CMD_WRITE_DISABLE;
+
+		status = spi_write_then_read(spi, buf, 2, NULL, 0);
+		if (status < 0) {
+			dev_err(&spi->dev, "control register write error %d\n",
+					status);
+			return status;
+		}
+
+		addr = RTC_ADDR_CTRL << 1 | RTC_CMD_READ;
+		status = spi_write_then_read(spi, &addr, sizeof(addr), buf, 1);
+		if (status < 0) {
+			dev_err(&spi->dev,
+					"error %d reading control register\n",
+					status);
+			return status;
+		}
+
+		if (buf[0] != RTC_CMD_WRITE_DISABLE) {
+			dev_err(&spi->dev, "failed to detect chip\n");
+			return -ENODEV;
+		}
+	}
 
-	/* Start RTC */
-	ds1302_writebyte(RTC_ADDR_SEC, ds1302_readbyte(RTC_ADDR_SEC) & ~0x80);
+	spi_set_drvdata(spi, spi);
 
-	ds1302_writebyte(RTC_ADDR_CTRL, RTC_CMD_WRITE_DISABLE);
+	rtc = devm_rtc_device_register(&spi->dev, "ds1302",
+			&ds1302_rtc_ops, THIS_MODULE);
+	if (IS_ERR(rtc)) {
+		status = PTR_ERR(rtc);
+		dev_err(&spi->dev, "error %d registering rtc\n", status);
+		return status;
+	}
 
 	return 0;
 }
 
-static int ds1302_rtc_ioctl(struct device *dev, unsigned int cmd,
-			    unsigned long arg)
+static int ds1302_remove(struct spi_device *spi)
 {
-	switch (cmd) {
-#ifdef RTC_SET_CHARGE
-	case RTC_SET_CHARGE:
-	{
-		int tcs_val;
-
-		if (copy_from_user(&tcs_val, (int __user *)arg, sizeof(int)))
-			return -EFAULT;
-
-		ds1302_writebyte(RTC_ADDR_TCR, (0xa0 | tcs_val * 0xf));
-		return 0;
-	}
-#endif
-	}
-
-	return -ENOIOCTLCMD;
+	spi_set_drvdata(spi, NULL);
+	return 0;
 }
 
-static struct rtc_class_ops ds1302_rtc_ops = {
-	.read_time	= ds1302_rtc_read_time,
-	.set_time	= ds1302_rtc_set_time,
-	.ioctl		= ds1302_rtc_ioctl,
+#ifdef CONFIG_OF
+static const struct of_device_id ds1302_dt_ids[] = {
+	{ .compatible = "maxim,rtc-ds1302", },
+	{ /* sentinel */ }
 };
+MODULE_DEVICE_TABLE(of, ds1302_dt_ids);
+#endif
 
-static int __init ds1302_rtc_probe(struct platform_device *pdev)
-{
-	struct rtc_device *rtc;
-
-	if (ds1302_hw_init()) {
-		dev_err(&pdev->dev, "Failed to init communication channel");
-		return -EINVAL;
-	}
-
-	/* Reset */
-	ds1302_reset();
-
-	/* Write a magic value to the DS1302 RAM, and see if it sticks. */
-	ds1302_writebyte(RTC_ADDR_RAM0, 0x42);
-	if (ds1302_readbyte(RTC_ADDR_RAM0) != 0x42) {
-		dev_err(&pdev->dev, "Failed to probe");
-		return -ENODEV;
-	}
-
-	rtc = devm_rtc_device_register(&pdev->dev, "ds1302",
-					   &ds1302_rtc_ops, THIS_MODULE);
-	if (IS_ERR(rtc))
-		return PTR_ERR(rtc);
-
-	platform_set_drvdata(pdev, rtc);
-
-	return 0;
-}
-
-static struct platform_driver ds1302_platform_driver = {
-	.driver		= {
-		.name	= DRV_NAME,
-	},
+static struct spi_driver ds1302_driver = {
+	.driver.name	= "rtc-ds1302",
+	.driver.of_match_table = of_match_ptr(ds1302_dt_ids),
+	.probe		= ds1302_probe,
+	.remove		= ds1302_remove,
 };
 
-module_platform_driver_probe(ds1302_platform_driver, ds1302_rtc_probe);
+module_spi_driver(ds1302_driver);
 
 MODULE_DESCRIPTION("Dallas DS1302 RTC driver");
 MODULE_VERSION(DRV_VERSION);
-- 
2.6.3

Re: [PATCH v6] rtc: rewrite DS1302 using SPI

[Rob Herring]

On Mon, Feb 22, 2016 at 04:41:22AM +0300, Sergei Ianovich wrote:
> DS1302 is half-duplex SPI device. The driver respects this fact now.
> 
> Pin configurations should be implemented using SPI subsystem.
> 
> Signed-off-by: Sergei Ianovich <ynvich-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> CC: Alexandre Belloni <alexandre.belloni-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
> CC: Rob Herring <robh-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
> ---
>    v5..v6
>    * rewrite the driver as an SPI slave device
>    * use "maxim" for vendor name per Kconfig
>    * stop touching device RAM in device presence test
>    * only return time from device if valid
>    * use burst mode for reading/writing time
>    * droppped charging control. I cannot test it, and it looks broken
> 
>    v4..v5
>    * drop THIS_MODULE from struct platform driver
>    * use "dallas" for vendor name per vendor-prefixes.txt
> 
>    v3..v4
>    * move DTS bindings to a different patch
> 
>    v2..v3
>    * use usleep_range instead of custom nsleep
>    * number change (07/16 -> 09/21)
> 
>    v0..v2
>    * use device tree
>    * use devm helpers where possible
> 
>  .../devicetree/bindings/rtc/rtc-ds1302.txt         |  46 +++
>  drivers/rtc/Kconfig                                |  15 +-
>  drivers/rtc/rtc-ds1302.c                           | 348 ++++++++++-----------
>  3 files changed, 212 insertions(+), 197 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/rtc/rtc-ds1302.txt
> 
> diff --git a/Documentation/devicetree/bindings/rtc/rtc-ds1302.txt b/Documentation/devicetree/bindings/rtc/rtc-ds1302.txt
> new file mode 100644
> index 0000000..b6c0973
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/rtc/rtc-ds1302.txt
> @@ -0,0 +1,46 @@
> +* Maxim/Dallas Semiconductor DS-1302 RTC
> +
> +Simple device which could be used to store date/time between reboots.
> +
> +The device uses the standard MicroWire half-duplex transfer timing.
> +Master output is set on low clock and sensed by the RTC on the rising
> +edge. Master input is set by the RTC on the trailing edge and is sensed
> +by the master on low clock.
> +
> +Required properties:
> +
> +- compatible : Should be "maxim,rtc-ds1302"

Just maxim,ds1032. RTC is implied by the part number and inline with 
existing dallas,ds1307.

> +
> +Required SPI properties:
> +
> +- reg : Should be address of the device chip select within
> +  the controller.
> +
> +- spi-max-frequency : DS-1302 has 500 kHz if powered at 2.2V,
> +  and 2MHz if powered at 5V.
> +
> +- spi-3wire : The device has a shared signal IN/OUT line.
> +
> +- spi-lsb-first : DS-1302 requires least significant bit first
> +  transfers.
> +
> +- spi-cs-high: DS-1302 has active high chip select line. This is
> +  required unless inverted in hardware.
> +
> +Example:
> +
> +spi0@901c {

spi@...

> +	#address-cells = <1>;
> +	#size-cells = <0>;
> +	compatible = "icpdas,spi-lp8841-rtc";

And this will need updating...

> +	reg = <0x901c 0x1>;
> +
> +	rtc@0 {
> +		compatible = "maxim,rtc-ds1302";
> +		reg = <0>;
> +		spi-max-frequency = <500000>;
> +		spi-3wire;
> +		spi-lsb-first;
> +		spi-cs-high;
> +	};
> +};

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[PATCH v7] rtc: rewrite DS1302 using SPI

[Sergei Ianovich]

DS1302 is half-duplex SPI device. The driver respects this fact now.

Pin configurations should be implemented using SPI subsystem.

Signed-off-by: Sergei Ianovich <ynvich@gmail.com>
CC: Alexandre Belloni <alexandre.belloni@free-electrons.com>
CC: Rob Herring <robh@kernel.org>

   v6..v7
   * change binding and doc file names

   v5..v6
   * rewrite the driver as an SPI slave device
   * use "maxim" for vendor name per Kconfig
   * stop changing device RAM in device presence test
   * only return time from device if valid
   * use burst mode for reading/writing time
   * dropped charging control. I cannot test it, and it looks broken

   v4..v5
   * drop THIS_MODULE from struct platform driver
   * use "dallas" for vendor name per vendor-prefixes.txt

   v3..v4
   * move DTS bindings to a different patch

   v2..v3
   * use usleep_range instead of custom nsleep
   * number change (07/16 -> 09/21)

   v0..v2
   * use device tree
   * use devm helpers where possible
---
 .../devicetree/bindings/rtc/maxim-ds1302.txt       |  46 +++
 drivers/rtc/Kconfig                                |  15 +-
 drivers/rtc/rtc-ds1302.c                           | 348 ++++++++++-----------
 3 files changed, 212 insertions(+), 197 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/rtc/maxim-ds1302.txt

diff --git a/Documentation/devicetree/bindings/rtc/maxim-ds1302.txt b/Documentation/devicetree/bindings/rtc/maxim-ds1302.txt
new file mode 100644
index 0000000..ba470c5
--- /dev/null
+++ b/Documentation/devicetree/bindings/rtc/maxim-ds1302.txt
@@ -0,0 +1,46 @@
+* Maxim/Dallas Semiconductor DS-1302 RTC
+
+Simple device which could be used to store date/time between reboots.
+
+The device uses the standard MicroWire half-duplex transfer timing.
+Master output is set on low clock and sensed by the RTC on the rising
+edge. Master input is set by the RTC on the trailing edge and is sensed
+by the master on low clock.
+
+Required properties:
+
+- compatible : Should be "maxim,ds1302"
+
+Required SPI properties:
+
+- reg : Should be address of the device chip select within
+  the controller.
+
+- spi-max-frequency : DS-1302 has 500 kHz if powered at 2.2V,
+  and 2MHz if powered at 5V.
+
+- spi-3wire : The device has a shared signal IN/OUT line.
+
+- spi-lsb-first : DS-1302 requires least significant bit first
+  transfers.
+
+- spi-cs-high: DS-1302 has active high chip select line. This is
+  required unless inverted in hardware.
+
+Example:
+
+spi@901c {
+	#address-cells = <1>;
+	#size-cells = <0>;
+	compatible = "icpdas,lp8841-spi-rtc";
+	reg = <0x901c 0x1>;
+
+	rtc@0 {
+		compatible = "maxim,ds1302";
+		reg = <0>;
+		spi-max-frequency = <500000>;
+		spi-3wire;
+		spi-lsb-first;
+		spi-cs-high;
+	};
+};
diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 376322f..e20e804 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -646,6 +646,15 @@ config RTC_DRV_M41T94
 	  This driver can also be built as a module. If so, the module
 	  will be called rtc-m41t94.
 
+config RTC_DRV_DS1302
+	tristate "Dallas/Maxim DS1302"
+	depends on SPI
+	help
+	  If you say yes here you get support for the Dallas DS1302 RTC chips.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called rtc-ds1302.
+
 config RTC_DRV_DS1305
 	tristate "Dallas/Maxim DS1305/DS1306"
 	help
@@ -811,12 +820,6 @@ config RTC_DRV_DS1286
 	help
 	  If you say yes here you get support for the Dallas DS1286 RTC chips.
 
-config RTC_DRV_DS1302
-	tristate "Dallas DS1302"
-	depends on SH_SECUREEDGE5410
-	help
-	  If you say yes here you get support for the Dallas DS1302 RTC chips.
-
 config RTC_DRV_DS1511
 	tristate "Dallas DS1511"
 	depends on HAS_IOMEM
diff --git a/drivers/rtc/rtc-ds1302.c b/drivers/rtc/rtc-ds1302.c
index 6bef7a5..5cdc0f2 100644
--- a/drivers/rtc/rtc-ds1302.c
+++ b/drivers/rtc/rtc-ds1302.c
@@ -9,16 +9,17 @@
  * this archive for more details.
  */
 
+#include <linux/bcd.h>
 #include <linux/init.h>
-#include <linux/module.h>
+#include <linux/io.h>
 #include <linux/kernel.h>
-#include <linux/platform_device.h>
+#include <linux/module.h>
+#include <linux/of.h>
 #include <linux/rtc.h>
-#include <linux/io.h>
-#include <linux/bcd.h>
+#include <linux/spi/spi.h>
 
 #define DRV_NAME	"rtc-ds1302"
-#define DRV_VERSION	"0.1.1"
+#define DRV_VERSION	"1.0.0"
 
 #define	RTC_CMD_READ	0x81		/* Read command */
 #define	RTC_CMD_WRITE	0x80		/* Write command */
@@ -28,6 +29,8 @@
 
 #define RTC_ADDR_RAM0	0x20		/* Address of RAM0 */
 #define RTC_ADDR_TCR	0x08		/* Address of trickle charge register */
+#define RTC_CLCK_BURST	0x1F		/* Address of clock burst */
+#define	RTC_CLCK_LEN	0x08		/* Size of clock burst */
 #define	RTC_ADDR_CTRL	0x07		/* Address of control register */
 #define	RTC_ADDR_YEAR	0x06		/* Address of year register */
 #define	RTC_ADDR_DAY	0x05		/* Address of day of week register */
@@ -37,217 +40,180 @@
 #define	RTC_ADDR_MIN	0x01		/* Address of minute register */
 #define	RTC_ADDR_SEC	0x00		/* Address of second register */
 
-#ifdef CONFIG_SH_SECUREEDGE5410
-#include <asm/rtc.h>
-#include <mach/secureedge5410.h>
-
-#define	RTC_RESET	0x1000
-#define	RTC_IODATA	0x0800
-#define	RTC_SCLK	0x0400
-
-#define set_dp(x)	SECUREEDGE_WRITE_IOPORT(x, 0x1c00)
-#define get_dp()	SECUREEDGE_READ_IOPORT()
-#define ds1302_set_tx()
-#define ds1302_set_rx()
-
-static inline int ds1302_hw_init(void)
+static int ds1302_rtc_set_time(struct device *dev, struct rtc_time *time)
 {
-	return 0;
+	struct spi_device	*spi = dev_get_drvdata(dev);
+	u8		buf[1 + RTC_CLCK_LEN];
+	u8		*bp = buf;
+	int		status;
+
+	/* Enable writing */
+	bp = buf;
+	*bp++ = RTC_ADDR_CTRL << 1 | RTC_CMD_WRITE;
+	*bp++ = RTC_CMD_WRITE_ENABLE;
+
+	status = spi_write_then_read(spi, buf, 2,
+			NULL, 0);
+	if (!status)
+		return status;
+
+	/* Write registers starting at the first time/date address. */
+	bp = buf;
+	*bp++ = RTC_CLCK_BURST << 1 | RTC_CMD_WRITE;
+
+	*bp++ = bin2bcd(time->tm_sec);
+	*bp++ = bin2bcd(time->tm_min);
+	*bp++ = bin2bcd(time->tm_hour);
+	*bp++ = bin2bcd(time->tm_mday);
+	*bp++ = bin2bcd(time->tm_mon + 1);
+	*bp++ = time->tm_wday;
+	*bp++ = bin2bcd(time->tm_year % 100);
+	*bp++ = RTC_CMD_WRITE_DISABLE;
+
+	/* use write-then-read since dma from stack is nonportable */
+	return spi_write_then_read(spi, buf, sizeof(buf),
+			NULL, 0);
 }
 
-static inline void ds1302_reset(void)
+static int ds1302_rtc_get_time(struct device *dev, struct rtc_time *time)
 {
-	set_dp(get_dp() & ~(RTC_RESET | RTC_IODATA | RTC_SCLK));
+	struct spi_device	*spi = dev_get_drvdata(dev);
+	u8		addr = RTC_CLCK_BURST << 1 | RTC_CMD_READ;
+	u8		buf[RTC_CLCK_LEN - 1];
+	int		status;
+
+	/* Use write-then-read to get all the date/time registers
+	 * since dma from stack is nonportable
+	 */
+	status = spi_write_then_read(spi, &addr, sizeof(addr),
+			buf, sizeof(buf));
+	if (status < 0)
+		return status;
+
+	/* Decode the registers */
+	time->tm_sec = bcd2bin(buf[RTC_ADDR_SEC]);
+	time->tm_min = bcd2bin(buf[RTC_ADDR_MIN]);
+	time->tm_hour = bcd2bin(buf[RTC_ADDR_HOUR]);
+	time->tm_wday = buf[RTC_ADDR_DAY] - 1;
+	time->tm_mday = bcd2bin(buf[RTC_ADDR_DATE]);
+	time->tm_mon = bcd2bin(buf[RTC_ADDR_MON]) - 1;
+	time->tm_year = bcd2bin(buf[RTC_ADDR_YEAR]) + 100;
+
+	/* Time may not be set */
+	return rtc_valid_tm(time);
 }
 
-static inline void ds1302_clock(void)
-{
-	set_dp(get_dp() | RTC_SCLK);	/* clock high */
-	set_dp(get_dp() & ~RTC_SCLK);	/* clock low */
-}
-
-static inline void ds1302_start(void)
-{
-	set_dp(get_dp() | RTC_RESET);
-}
-
-static inline void ds1302_stop(void)
-{
-	set_dp(get_dp() & ~RTC_RESET);
-}
-
-static inline void ds1302_txbit(int bit)
-{
-	set_dp((get_dp() & ~RTC_IODATA) | (bit ? RTC_IODATA : 0));
-}
-
-static inline int ds1302_rxbit(void)
-{
-	return !!(get_dp() & RTC_IODATA);
-}
-
-#else
-#error "Add support for your platform"
-#endif
+static struct rtc_class_ops ds1302_rtc_ops = {
+	.read_time	= ds1302_rtc_get_time,
+	.set_time	= ds1302_rtc_set_time,
+};
 
-static void ds1302_sendbits(unsigned int val)
+static int ds1302_probe(struct spi_device *spi)
 {
-	int i;
-
-	ds1302_set_tx();
-
-	for (i = 8; (i); i--, val >>= 1) {
-		ds1302_txbit(val & 0x1);
-		ds1302_clock();
+	struct rtc_device	*rtc;
+	u8		addr;
+	u8		buf[4];
+	u8		*bp = buf;
+	int		status;
+
+	/* Sanity check board setup data.  This may be hooked up
+	 * in 3wire mode, but we don't care.  Note that unless
+	 * there's an inverter in place, this needs SPI_CS_HIGH!
+	 */
+	if (spi->bits_per_word && (spi->bits_per_word != 8)) {
+		dev_err(&spi->dev, "bad word length\n");
+		return -EINVAL;
+	} else if (spi->max_speed_hz > 2000000) {
+		dev_err(&spi->dev, "speed is too high\n");
+		return -EINVAL;
+	} else if (spi->mode & SPI_CPHA) {
+		dev_err(&spi->dev, "bad mode\n");
+		return -EINVAL;
 	}
-}
-
-static unsigned int ds1302_recvbits(void)
-{
-	unsigned int val;
-	int i;
-
-	ds1302_set_rx();
 
-	for (i = 0, val = 0; (i < 8); i++) {
-		val |= (ds1302_rxbit() << i);
-		ds1302_clock();
+	addr = RTC_ADDR_CTRL << 1 | RTC_CMD_READ;
+	status = spi_write_then_read(spi, &addr, sizeof(addr), buf, 1);
+	if (status < 0) {
+		dev_err(&spi->dev, "control register read error %d\n",
+				status);
+		return status;
 	}
 
-	return val;
-}
-
-static unsigned int ds1302_readbyte(unsigned int addr)
-{
-	unsigned int val;
-
-	ds1302_reset();
-
-	ds1302_start();
-	ds1302_sendbits(((addr & 0x3f) << 1) | RTC_CMD_READ);
-	val = ds1302_recvbits();
-	ds1302_stop();
-
-	return val;
-}
-
-static void ds1302_writebyte(unsigned int addr, unsigned int val)
-{
-	ds1302_reset();
-
-	ds1302_start();
-	ds1302_sendbits(((addr & 0x3f) << 1) | RTC_CMD_WRITE);
-	ds1302_sendbits(val);
-	ds1302_stop();
-}
-
-static int ds1302_rtc_read_time(struct device *dev, struct rtc_time *tm)
-{
-	tm->tm_sec	= bcd2bin(ds1302_readbyte(RTC_ADDR_SEC));
-	tm->tm_min	= bcd2bin(ds1302_readbyte(RTC_ADDR_MIN));
-	tm->tm_hour	= bcd2bin(ds1302_readbyte(RTC_ADDR_HOUR));
-	tm->tm_wday	= bcd2bin(ds1302_readbyte(RTC_ADDR_DAY));
-	tm->tm_mday	= bcd2bin(ds1302_readbyte(RTC_ADDR_DATE));
-	tm->tm_mon	= bcd2bin(ds1302_readbyte(RTC_ADDR_MON)) - 1;
-	tm->tm_year	= bcd2bin(ds1302_readbyte(RTC_ADDR_YEAR));
-
-	if (tm->tm_year < 70)
-		tm->tm_year += 100;
-
-	dev_dbg(dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
-		"mday=%d, mon=%d, year=%d, wday=%d\n",
-		__func__,
-		tm->tm_sec, tm->tm_min, tm->tm_hour,
-		tm->tm_mday, tm->tm_mon + 1, tm->tm_year, tm->tm_wday);
-
-	return rtc_valid_tm(tm);
-}
-
-static int ds1302_rtc_set_time(struct device *dev, struct rtc_time *tm)
-{
-	ds1302_writebyte(RTC_ADDR_CTRL, RTC_CMD_WRITE_ENABLE);
-	/* Stop RTC */
-	ds1302_writebyte(RTC_ADDR_SEC, ds1302_readbyte(RTC_ADDR_SEC) | 0x80);
-
-	ds1302_writebyte(RTC_ADDR_SEC, bin2bcd(tm->tm_sec));
-	ds1302_writebyte(RTC_ADDR_MIN, bin2bcd(tm->tm_min));
-	ds1302_writebyte(RTC_ADDR_HOUR, bin2bcd(tm->tm_hour));
-	ds1302_writebyte(RTC_ADDR_DAY, bin2bcd(tm->tm_wday));
-	ds1302_writebyte(RTC_ADDR_DATE, bin2bcd(tm->tm_mday));
-	ds1302_writebyte(RTC_ADDR_MON, bin2bcd(tm->tm_mon + 1));
-	ds1302_writebyte(RTC_ADDR_YEAR, bin2bcd(tm->tm_year % 100));
+	if ((buf[0] & ~RTC_CMD_WRITE_DISABLE) != 0) {
+		status = spi_write_then_read(spi, &addr, sizeof(addr), buf, 1);
+		if (status < 0) {
+			dev_err(&spi->dev, "control register read error %d\n",
+					status);
+			return status;
+		}
+
+		if ((buf[0] & ~RTC_CMD_WRITE_DISABLE) != 0) {
+			dev_err(&spi->dev, "junk in control register\n");
+			return -ENODEV;
+		}
+	}
+	if (buf[0] == 0) {
+		bp = buf;
+		*bp++ = RTC_ADDR_CTRL << 1 | RTC_CMD_WRITE;
+		*bp++ = RTC_CMD_WRITE_DISABLE;
+
+		status = spi_write_then_read(spi, buf, 2, NULL, 0);
+		if (status < 0) {
+			dev_err(&spi->dev, "control register write error %d\n",
+					status);
+			return status;
+		}
+
+		addr = RTC_ADDR_CTRL << 1 | RTC_CMD_READ;
+		status = spi_write_then_read(spi, &addr, sizeof(addr), buf, 1);
+		if (status < 0) {
+			dev_err(&spi->dev,
+					"error %d reading control register\n",
+					status);
+			return status;
+		}
+
+		if (buf[0] != RTC_CMD_WRITE_DISABLE) {
+			dev_err(&spi->dev, "failed to detect chip\n");
+			return -ENODEV;
+		}
+	}
 
-	/* Start RTC */
-	ds1302_writebyte(RTC_ADDR_SEC, ds1302_readbyte(RTC_ADDR_SEC) & ~0x80);
+	spi_set_drvdata(spi, spi);
 
-	ds1302_writebyte(RTC_ADDR_CTRL, RTC_CMD_WRITE_DISABLE);
+	rtc = devm_rtc_device_register(&spi->dev, "ds1302",
+			&ds1302_rtc_ops, THIS_MODULE);
+	if (IS_ERR(rtc)) {
+		status = PTR_ERR(rtc);
+		dev_err(&spi->dev, "error %d registering rtc\n", status);
+		return status;
+	}
 
 	return 0;
 }
 
-static int ds1302_rtc_ioctl(struct device *dev, unsigned int cmd,
-			    unsigned long arg)
+static int ds1302_remove(struct spi_device *spi)
 {
-	switch (cmd) {
-#ifdef RTC_SET_CHARGE
-	case RTC_SET_CHARGE:
-	{
-		int tcs_val;
-
-		if (copy_from_user(&tcs_val, (int __user *)arg, sizeof(int)))
-			return -EFAULT;
-
-		ds1302_writebyte(RTC_ADDR_TCR, (0xa0 | tcs_val * 0xf));
-		return 0;
-	}
-#endif
-	}
-
-	return -ENOIOCTLCMD;
+	spi_set_drvdata(spi, NULL);
+	return 0;
 }
 
-static struct rtc_class_ops ds1302_rtc_ops = {
-	.read_time	= ds1302_rtc_read_time,
-	.set_time	= ds1302_rtc_set_time,
-	.ioctl		= ds1302_rtc_ioctl,
+#ifdef CONFIG_OF
+static const struct of_device_id ds1302_dt_ids[] = {
+	{ .compatible = "maxim,ds1302", },
+	{ /* sentinel */ }
 };
+MODULE_DEVICE_TABLE(of, ds1302_dt_ids);
+#endif
 
-static int __init ds1302_rtc_probe(struct platform_device *pdev)
-{
-	struct rtc_device *rtc;
-
-	if (ds1302_hw_init()) {
-		dev_err(&pdev->dev, "Failed to init communication channel");
-		return -EINVAL;
-	}
-
-	/* Reset */
-	ds1302_reset();
-
-	/* Write a magic value to the DS1302 RAM, and see if it sticks. */
-	ds1302_writebyte(RTC_ADDR_RAM0, 0x42);
-	if (ds1302_readbyte(RTC_ADDR_RAM0) != 0x42) {
-		dev_err(&pdev->dev, "Failed to probe");
-		return -ENODEV;
-	}
-
-	rtc = devm_rtc_device_register(&pdev->dev, "ds1302",
-					   &ds1302_rtc_ops, THIS_MODULE);
-	if (IS_ERR(rtc))
-		return PTR_ERR(rtc);
-
-	platform_set_drvdata(pdev, rtc);
-
-	return 0;
-}
-
-static struct platform_driver ds1302_platform_driver = {
-	.driver		= {
-		.name	= DRV_NAME,
-	},
+static struct spi_driver ds1302_driver = {
+	.driver.name	= "rtc-ds1302",
+	.driver.of_match_table = of_match_ptr(ds1302_dt_ids),
+	.probe		= ds1302_probe,
+	.remove		= ds1302_remove,
 };
 
-module_platform_driver_probe(ds1302_platform_driver, ds1302_rtc_probe);
+module_spi_driver(ds1302_driver);
 
 MODULE_DESCRIPTION("Dallas DS1302 RTC driver");
 MODULE_VERSION(DRV_VERSION);
-- 
2.7.0

Re: [PATCH v7] rtc: rewrite DS1302 using SPI

[Rob Herring]

On Tue, Feb 23, 2016 at 01:54:57PM +0300, Sergei Ianovich wrote:
> DS1302 is half-duplex SPI device. The driver respects this fact now.
> 
> Pin configurations should be implemented using SPI subsystem.
> 
> Signed-off-by: Sergei Ianovich <ynvich-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> CC: Alexandre Belloni <alexandre.belloni-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
> CC: Rob Herring <robh-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
> 
>    v6..v7
>    * change binding and doc file names
> 
>    v5..v6
>    * rewrite the driver as an SPI slave device
>    * use "maxim" for vendor name per Kconfig
>    * stop changing device RAM in device presence test
>    * only return time from device if valid
>    * use burst mode for reading/writing time
>    * dropped charging control. I cannot test it, and it looks broken
> 
>    v4..v5
>    * drop THIS_MODULE from struct platform driver
>    * use "dallas" for vendor name per vendor-prefixes.txt
> 
>    v3..v4
>    * move DTS bindings to a different patch
> 
>    v2..v3
>    * use usleep_range instead of custom nsleep
>    * number change (07/16 -> 09/21)
> 
>    v0..v2
>    * use device tree
>    * use devm helpers where possible
> ---
>  .../devicetree/bindings/rtc/maxim-ds1302.txt       |  46 +++

Acked-by: Rob Herring <robh-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>

>  drivers/rtc/Kconfig                                |  15 +-
>  drivers/rtc/rtc-ds1302.c                           | 348 ++++++++++-----------
>  3 files changed, 212 insertions(+), 197 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/rtc/maxim-ds1302.txt
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Re: [PATCH v7] rtc: rewrite DS1302 using SPI

[Alexandre Belloni]

Hi,

Thank you for your work!

On 23/02/2016 at 13:54:57 +0300, Sergei Ianovich wrote :
> -#ifdef CONFIG_SH_SECUREEDGE5410
> -#include <asm/rtc.h>
> -#include <mach/secureedge5410.h>
> -
> -#define	RTC_RESET	0x1000
> -#define	RTC_IODATA	0x0800
> -#define	RTC_SCLK	0x0400
> -
> -#define set_dp(x)	SECUREEDGE_WRITE_IOPORT(x, 0x1c00)
> -#define get_dp()	SECUREEDGE_READ_IOPORT()
> -#define ds1302_set_tx()
> -#define ds1302_set_rx()
> -

I would like to have a solution for secureedge5410 even if it is
untested. Else, we are breaking an existing platform without any
solution.

I've put the sh maintainers in copy, maybe they have an opinion. Else
I'll let your patch sit in linux-next for the next cycle.

I have further cleanups in that driver but they can probably be done
later.

-- 
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

Re: [PATCH v7] rtc: rewrite DS1302 using SPI

[Sergei Ianovich]

On Tue, 2016-03-15 at 01:18 +0100, Alexandre Belloni wrote:
> I would like to have a solution for secureedge5410 even if it is
> untested. Else, we are breaking an existing platform without any
> solution.
> 
> I've put the sh maintainers in copy, maybe they have an opinion. Else
> I'll let your patch sit in linux-next for the next cycle.

secureedge5410 will need an SPI host driver. The driver will be similar
to the one I did for lp8841. I can make a clone for secureedge5410, but
I cannot test it.

The only reason, I didn't file the patch for secureedge5410, is I
thought SPI people won't accept an untested patch.

Re: [PATCH v7] rtc: rewrite DS1302 using SPI

[Alexandre Belloni]

On 23/02/2016 at 13:54:57 +0300, Sergei Ianovich wrote :
> DS1302 is half-duplex SPI device. The driver respects this fact now.
> 
> Pin configurations should be implemented using SPI subsystem.
> 
> Signed-off-by: Sergei Ianovich <ynvich-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> CC: Alexandre Belloni <alexandre.belloni-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>
> CC: Rob Herring <robh-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
> 
>    v6..v7
>    * change binding and doc file names
> 
>    v5..v6
>    * rewrite the driver as an SPI slave device
>    * use "maxim" for vendor name per Kconfig
>    * stop changing device RAM in device presence test
>    * only return time from device if valid
>    * use burst mode for reading/writing time
>    * dropped charging control. I cannot test it, and it looks broken
> 
>    v4..v5
>    * drop THIS_MODULE from struct platform driver
>    * use "dallas" for vendor name per vendor-prefixes.txt
> 
>    v3..v4
>    * move DTS bindings to a different patch
> 
>    v2..v3
>    * use usleep_range instead of custom nsleep
>    * number change (07/16 -> 09/21)
> 
>    v0..v2
>    * use device tree
>    * use devm helpers where possible
> ---
>  .../devicetree/bindings/rtc/maxim-ds1302.txt       |  46 +++
>  drivers/rtc/Kconfig                                |  15 +-
>  drivers/rtc/rtc-ds1302.c                           | 348 ++++++++++-----------
>  3 files changed, 212 insertions(+), 197 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/rtc/maxim-ds1302.txt
> 
Applied, thanks.

-- 
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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