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Date: Fri, 15 Feb 2013 13:50:37 +0200
From: Mika Westerberg <mika.westerberg@...ux.intel.com>
To: Christian Ruppert <christian.ruppert@...lis.com>
Cc: Wolfram Sang <w.sang@...gutronix.de>,
"Ben Dooks (embedded platforms)" <ben-linux@...ff.org>,
Grant Likely <grant.likely@...retlab.ca>,
Rob Herring <rob.herring@...xeda.com>,
Rob Landley <rob@...dley.net>,
devicetree-discuss@...ts.ozlabs.org, linux-doc@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-i2c@...r.kernel.org,
Vineet Gupta <Vineet.Gupta1@...opsys.com>,
Pierrick Hascoet <pierrick.hascoet@...lis.com>
Subject: Re: [PATCH] i2c-designware: Interrupt sharing and SDA hold time
On Fri, Feb 15, 2013 at 11:11:50AM +0100, Christian Ruppert wrote:
> This patch implements interrupt sharing and SDA hold time configuration in
> the designware i2c driver. Both functions are enabled through platform data
> or device tree. Tested with Linux-3.8rc4 (Synopsys ARC port, see
> https://github.com/foss-for-synopsys-dwc-arc-processors/linux/commits/arc-3.8-baseline).
>
> Signed-off-by: Christian Ruppert <christian.ruppert@...lis.com>
> Signed-off-by: Pierrick Hascoet <pierrick.hascoet@...lis.com>
> ---
> .../devicetree/bindings/i2c/i2c-designware.txt | 18 ++++++++++
> drivers/i2c/busses/i2c-designware-core.c | 6 +++
> drivers/i2c/busses/i2c-designware-core.h | 2 +
> drivers/i2c/busses/i2c-designware-platdrv.c | 34 +++++++++++++++++++-
> include/linux/i2c/i2c-designware.h | 13 +++++++
> 5 files changed, 72 insertions(+), 1 deletions(-)
> create mode 100644 include/linux/i2c/i2c-designware.h
>
> diff --git a/Documentation/devicetree/bindings/i2c/i2c-designware.txt b/Documentation/devicetree/bindings/i2c/i2c-designware.txt
> index e42a2ee..474386b 100644
> --- a/Documentation/devicetree/bindings/i2c/i2c-designware.txt
> +++ b/Documentation/devicetree/bindings/i2c/i2c-designware.txt
> @@ -10,6 +10,12 @@ Recommended properties :
>
> - clock-frequency : desired I2C bus clock frequency in Hz.
>
> +Optional properties :
> + - interrupts-shared : If this property is present, the interrupt line is
> + considered shared with other devices.
> + - sda-hold-time : If this property is present, the register SDA_HOLD will
> + be initialised with its value.
> +
> Example :
>
> i2c@...00 {
> @@ -20,3 +26,15 @@ Example :
> interrupts = <11>;
> clock-frequency = <400000>;
> };
> +
> + i2c@...0000 {
> + #address-cells = <1>;
> + #size-cells = <0>;
> + compatible = "snps,designware-i2c";
> + reg = <0x1120000 0x1000>;
> + interrupt-parent = <&ictl>;
> + interrupts = <12 1>;
> + interrupts-shared;
> + clock-frequency = <400000>;
> + sda-hold-time = <0x64>;
> + };
> diff --git a/drivers/i2c/busses/i2c-designware-core.c b/drivers/i2c/busses/i2c-designware-core.c
> index cbba7db..36ba0b5 100644
> --- a/drivers/i2c/busses/i2c-designware-core.c
> +++ b/drivers/i2c/busses/i2c-designware-core.c
> @@ -34,6 +34,7 @@
> #include <linux/io.h>
> #include <linux/pm_runtime.h>
> #include <linux/delay.h>
> +#include <linux/i2c/i2c-designware.h>
> #include "i2c-designware-core.h"
>
> /*
> @@ -66,6 +67,7 @@
> #define DW_IC_STATUS 0x70
> #define DW_IC_TXFLR 0x74
> #define DW_IC_RXFLR 0x78
> +#define DW_IC_SDA_HOLD 0x7c
> #define DW_IC_TX_ABRT_SOURCE 0x80
> #define DW_IC_COMP_PARAM_1 0xf4
> #define DW_IC_COMP_TYPE 0xfc
> @@ -309,6 +311,10 @@ int i2c_dw_init(struct dw_i2c_dev *dev)
> dw_writel(dev, lcnt, DW_IC_FS_SCL_LCNT);
> dev_dbg(dev->dev, "Fast-mode HCNT:LCNT = %d:%d\n", hcnt, lcnt);
>
> + /* Configure SDA Hold Time if required */
> + if (dev->pdat_flags & I2C_DW_PDAT_FLAGS_SET_HOLDTIME)
> + dw_writel(dev, dev->sda_hold_time, DW_IC_SDA_HOLD);
AFAIK, DW_IC_SDA_HOLD minimum value is 1 so you could just do:
if (dev->sda_hold_time)
dw_writel(dev, dev->sda_hold_time, DW_IC_SDA_HOLD);
Also should this be configurable for standard and fast modes both?
Something like sm_sda_hold_time and fm_sda_hold_time?
> +
> /* Configure Tx/Rx FIFO threshold levels */
> dw_writel(dev, dev->tx_fifo_depth - 1, DW_IC_TX_TL);
> dw_writel(dev, 0, DW_IC_RX_TL);
> diff --git a/drivers/i2c/busses/i2c-designware-core.h b/drivers/i2c/busses/i2c-designware-core.h
> index 9c1840e..ef20477 100644
> --- a/drivers/i2c/busses/i2c-designware-core.h
> +++ b/drivers/i2c/busses/i2c-designware-core.h
> @@ -88,6 +88,8 @@ struct dw_i2c_dev {
> u32 master_cfg;
> unsigned int tx_fifo_depth;
> unsigned int rx_fifo_depth;
> + u32 sda_hold_time;
> + unsigned int pdat_flags;
> };
>
> #define ACCESS_SWAP 0x00000001
> diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
> index 343357a..2ad2da3 100644
> --- a/drivers/i2c/busses/i2c-designware-platdrv.c
> +++ b/drivers/i2c/busses/i2c-designware-platdrv.c
> @@ -34,11 +34,13 @@
> #include <linux/sched.h>
> #include <linux/err.h>
> #include <linux/interrupt.h>
> +#include <linux/of.h>
> #include <linux/of_i2c.h>
> #include <linux/platform_device.h>
> #include <linux/pm.h>
> #include <linux/io.h>
> #include <linux/slab.h>
> +#include <linux/i2c/i2c-designware.h>
> #include "i2c-designware-core.h"
>
> static struct i2c_algorithm i2c_dw_algo = {
> @@ -56,6 +58,28 @@ static int dw_i2c_probe(struct platform_device *pdev)
> struct i2c_adapter *adap;
> struct resource *mem, *ioarea;
> int irq, r;
> + unsigned long irqf;
> + struct i2c_designware_platform_data *pdat = pdev->dev.platform_data;
> +
> + if ((!pdat) && pdev->dev.of_node) {
> + struct device_node *node = pdev->dev.of_node;
> +
> + pdat = kmalloc(sizeof(struct i2c_designware_platform_data),
> + GFP_KERNEL);
> + if (!pdat)
> + return -ENOMEM;
> +
> + pdat->flags = 0;
> +
> + if (of_get_property(node, "interrupts-shared", NULL))
> + pdat->flags |= I2C_DW_PDAT_FLAGS_SHARE_IRQ;
> +
> + if (!of_property_read_u32(node, "sda-hold-time",
> + &pdat->sda_hold_time))
> + pdat->flags |= I2C_DW_PDAT_FLAGS_SET_HOLDTIME;
> +
> + pdev->dev.platform_data = pdat;
I do not understand why you need a separate platform data at all? Can't you
do it in a same way than the ACPI code?
And this probably doesn't apply to the i2c/next branch because we added the
ACPI enumeration there.
> + }
>
> /* NOTE: driver uses the static register mapping */
> mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> @@ -120,12 +144,20 @@ static int dw_i2c_probe(struct platform_device *pdev)
> dev->tx_fifo_depth = ((param1 >> 16) & 0xff) + 1;
> dev->rx_fifo_depth = ((param1 >> 8) & 0xff) + 1;
> }
> + dev->sda_hold_time = pdat->sda_hold_time;
> + dev->pdat_flags = pdat->flags;
> +
> r = i2c_dw_init(dev);
> if (r)
> goto err_iounmap;
>
> i2c_dw_disable_int(dev);
> - r = request_irq(dev->irq, i2c_dw_isr, IRQF_DISABLED, pdev->name, dev);
> +
> + irqf = IRQF_DISABLED;
> + if (dev->pdat_flags & I2C_DW_PDAT_FLAGS_SHARE_IRQ)
> + irqf |= IRQF_SHARED;
Please check Wolfram's i2c/next. This is set already there.
> +
> + r = request_irq(dev->irq, i2c_dw_isr, irqf, pdev->name, dev);
> if (r) {
> dev_err(&pdev->dev, "failure requesting irq %i\n", dev->irq);
> goto err_iounmap;
> diff --git a/include/linux/i2c/i2c-designware.h b/include/linux/i2c/i2c-designware.h
> new file mode 100644
> index 0000000..ea8192a
> --- /dev/null
> +++ b/include/linux/i2c/i2c-designware.h
> @@ -0,0 +1,13 @@
> +#ifndef __I2C_DESIGNWARE_H__
> +#define __I2C_DESIGNWARE_H__
> +
> +#include <linux/platform_device.h>
> +
> +struct i2c_designware_platform_data {
> + unsigned int flags;
> +#define I2C_DW_PDAT_FLAGS_SHARE_IRQ (1L<<0)
> +#define I2C_DW_PDAT_FLAGS_SET_HOLDTIME (1L<<1)
> + u32 sda_hold_time;
> +};
> +
> +#endif /* __I2C_DESIGNWARE_H__ */
> --
> 1.7.1
>
> --
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