Re: [PATCH] i2c: exynos5: add High Speed I2C controller driver

Naveen Krishna Ch
2013-03-20T16:26:42Z

On 12 March 2013 18:43, Simon Glass <sjg-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org> wrote:
> [please excuse my mailer html confusion]
>
> Hi Naveen,
>
> On Mon, Mar 11, 2013 at 9:32 PM, Naveen Krishna Chatradhi
> <ch.naveen-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org> wrote:
>>
>> Adds support for High Speed I2C driver found in Exynos5 and later
>> SoCs from Samsung. This driver currently supports Auto mode.
>>
>> Driver only supports Device Tree method.
>> Note: Added debugfs support for registers view, not tested.
>>
>> Signed-off-by: Taekgyun Ko <taeggyun.ko-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>
>> Signed-off-by: Naveen Krishna Chatradhi <ch.naveen-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>
>> Cc: R. Chandrasekar <rcsekar-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>
>> ---
>> Changes since v3: http://lkml.org/lkml/2012/12/28/46
>> 1. Added Documentation for DT bindings
>> 2. Removed the bus_num, as Doug's pick id from DT is merged in i2c/for-next
>> 3. Split the xfer function for better clarity.
>> 4. Streamlined code flow in isr, handled trans_status register in xfer_msg call.
>>
>> .../devicetree/bindings/i2c/i2c-exynos5.txt | 50 ++
>> drivers/i2c/busses/Kconfig | 7 +
>> drivers/i2c/busses/Makefile | 1 +
>> drivers/i2c/busses/i2c-exynos5.c | 743 ++++++++++++++++++++
>> 4 files changed, 801 insertions(+)
>> create mode 100644 Documentation/devicetree/bindings/i2c/i2c-exynos5.txt
>> create mode 100644 drivers/i2c/busses/i2c-exynos5.c
>>
>> diff --git a/Documentation/devicetree/bindings/i2c/i2c-exynos5.txt b/Documentation/devicetree/bindings/i2c/i2c-exynos5.txt
>> new file mode 100644
>> index 0000000..0bc9347
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/i2c/i2c-exynos5.txt
>> @@ -0,0 +1,50 @@
>> +* Samsung's High Speed I2C controller
>> +
>> +The Samsung's High Speed I2C controller is used to interface with I2C devices
>> +at various speeds ranging from 100khz to 3.4Mhz.
>> +
>> +Required properties:
>> + - compatible: value should be.
>> + (a) "samsung,exynos5-hsi2c", for i2c compatible with exynos5 hsi2c.
>> + - reg: physical base address of the controller and length of memory mapped
>> + region.
>> + - interrupts: interrupt number to the cpu.
>> +
>> + - Samsung GPIO variant (deprecated):
>> + - gpios: The order of the gpios should be the following: <SDA, SCL>.
>> + The gpio specifier depends on the gpio controller.
>> + - Pinctrl variant (preferred, if available):
>> + - pinctrl-0: Pin control group to be used for this controller.
>> + - pinctrl-names: Should contain only one value - "default".
>> +
>> +Optional properties:
>> + - samsung,hs-mode: Mode of operation, High speed or Fast speed mode. If not
>> + specified, default value is 0.
>> + - samsung,hs-clock-freq: Desired operating frequency in Hz of the bus.
>> + If not specified, the default value in Hz is 100000.
>> + - samsung,fs-clock-freq: Desired operarting frequency in Hz of the bus.
>> + If not specified, the default value in Hz is 100000.
>> +
>> +Example:
>> +
>> + hsi2c@12ca0000 {
>> + compatible = "samsung,exynos5-hsi2c";
>> + reg = <0x12ca0000 0x100>;
>> + interrupts = <56>;
>> + samsung,fs-clock-freq = <100000>;
>> + /* Samsung GPIO variant begins here */
>> + gpios = <&gpd1 2 0 /* SDA */
>> + &gpd1 3 0 /* SCL */>;
>> + /* Samsung GPIO variant ends here */
>> + /* Pinctrl variant begins here */
>> + pinctrl-0 = <&i2c4_bus>;
>> + pinctrl-names = "default";
>> + /* Pinctrl variant ends here */
>> + #address-cells = <1>;
>> + #size-cells = <0>;
>> +
>> + s2mps11_pmic@66 {
>> + compatible = "samsung,s2mps11-pmic";
>> + reg = <0x66>;
>> + };
>> + };
>> diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
>> index a3725de..78b4936 100644
>> --- a/drivers/i2c/busses/Kconfig
>> +++ b/drivers/i2c/busses/Kconfig
>> @@ -434,6 +434,13 @@ config I2C_EG20T
>> ML7213/ML7223/ML7831 is companion chip for Intel Atom E6xx series.
>> ML7213/ML7223/ML7831 is completely compatible for Intel EG20T PCH.
>>
>> +config I2C_EXYNOS5
>> + tristate "Exynos5 high-speed I2C driver"
>> + depends on ARCH_EXYNOS5 && OF
>> + help
>> + Say Y here to include support for High-speed I2C controller in the
>> + Exynos5 based Samsung SoCs.
>> +
>> config I2C_GPIO
>> tristate "GPIO-based bitbanging I2C"
>> depends on GENERIC_GPIO
>> diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
>> index 8f4fc23..b19366c 100644
>> --- a/drivers/i2c/busses/Makefile
>> +++ b/drivers/i2c/busses/Makefile
>> @@ -42,6 +42,7 @@ i2c-designware-platform-objs := i2c-designware-platdrv.o
>> obj-$(CONFIG_I2C_DESIGNWARE_PCI) += i2c-designware-pci.o
>> i2c-designware-pci-objs := i2c-designware-pcidrv.o
>> obj-$(CONFIG_I2C_EG20T) += i2c-eg20t.o
>> +obj-$(CONFIG_I2C_EXYNOS5) += i2c-exynos5.o
>> obj-$(CONFIG_I2C_GPIO) += i2c-gpio.o
>> obj-$(CONFIG_I2C_HIGHLANDER) += i2c-highlander.o
>> obj-$(CONFIG_I2C_IBM_IIC) += i2c-ibm_iic.o
>> diff --git a/drivers/i2c/busses/i2c-exynos5.c b/drivers/i2c/busses/i2c-exynos5.c
>> new file mode 100644
>> index 0000000..fe30b0b
>> --- /dev/null
>> +++ b/drivers/i2c/busses/i2c-exynos5.c
>> @@ -0,0 +1,743 @@
>> +/**
>> + * i2c-exynos5.c - Samsung Exynos5 I2C Controller Driver
>> + *
>> + * Copyright (C) 2013 Samsung Electronics Co., Ltd.
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License version 2 as
>> + * published by the Free Software Foundation.
>> +*/
>> +
>> +#include <linux/kernel.h>
>> +#include <linux/module.h>
>> +#include <linux/debugfs.h>
>> +
>> +#include <linux/i2c.h>
>> +#include <linux/init.h>
>> +#include <linux/time.h>
>> +#include <linux/interrupt.h>
>> +#include <linux/delay.h>
>> +#include <linux/errno.h>
>> +#include <linux/err.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/pm_runtime.h>
>> +#include <linux/clk.h>
>> +#include <linux/slab.h>
>> +#include <linux/io.h>
>> +#include <linux/of_address.h>
>> +#include <linux/of_gpio.h>
>> +#include <linux/of_irq.h>
>> +#include <linux/of_i2c.h>
>> +
>> +/* Register Map */
>> +#define HSI2C_CTL 0x00
>> +#define HSI2C_FIFO_CTL 0x04
>> +#define HSI2C_TRAILIG_CTL 0x08
>> +#define HSI2C_CLK_CTL 0x0C
>> +#define HSI2C_CLK_SLOT 0x10
>> +#define HSI2C_INT_ENABLE 0x20
>> +#define HSI2C_INT_STATUS 0x24
>> +#define HSI2C_ERR_STATUS 0x2C
>> +#define HSI2C_FIFO_STATUS 0x30
>> +#define HSI2C_TX_DATA 0x34
>> +#define HSI2C_RX_DATA 0x38
>> +#define HSI2C_CONF 0x40
>> +#define HSI2C_AUTO_CONF 0x44
>> +#define HSI2C_TIMEOUT 0x48
>> +#define HSI2C_MANUAL_CMD 0x4C
>> +#define HSI2C_TRANS_STATUS 0x50
>> +#define HSI2C_TIMING_HS1 0x54
>> +#define HSI2C_TIMING_HS2 0x58
>> +#define HSI2C_TIMING_HS3 0x5C
>> +#define HSI2C_TIMING_FS1 0x60
>> +#define HSI2C_TIMING_FS2 0x64
>> +#define HSI2C_TIMING_FS3 0x68
>> +#define HSI2C_TIMING_SLA 0x6C
>> +#define HSI2C_ADDR 0x70
>> +
>> +/* I2C_CTL Register bits */
>> +#define HSI2C_FUNC_MODE_I2C (1u << 0)
>> +#define HSI2C_MASTER (1u << 3)
>> +#define HSI2C_RXCHON (1u << 6)
>> +#define HSI2C_TXCHON (1u << 7)
>> +#define HSI2C_SW_RST (1u << 31)
>> +
>> +/* I2C_FIFO_CTL Register bits */
>> +#define HSI2C_RXFIFO_EN (1u << 0)
>> +#define HSI2C_TXFIFO_EN (1u << 1)
>> +#define HSI2C_TXFIFO_TRIGGER_LEVEL (0x20 << 16)
>> +#define HSI2C_RXFIFO_TRIGGER_LEVEL (0x20 << 4)
>> +
>> +/* I2C_TRAILING_CTL Register bits */
>> +#define HSI2C_TRAILING_COUNT (0xf)
>> +
>> +/* I2C_INT_EN Register bits */
>> +#define HSI2C_INT_TX_ALMOSTEMPTY_EN (1u << 0)
>> +#define HSI2C_INT_RX_ALMOSTFULL_EN (1u << 1)
>> +#define HSI2C_INT_TRAILING_EN (1u << 6)
>> +#define HSI2C_INT_I2C_EN (1u << 9)
>> +
>> +/* I2C_FIFO_STAT Register bits */
>> +#define HSI2C_RX_FIFO_EMPTY (1u << 24)
>> +#define HSI2C_RX_FIFO_FULL (1u << 23)
>> +#define HSI2C_TX_FIFO_EMPTY (1u << 8)
>> +#define HSI2C_TX_FIFO_FULL (1u << 7)
>> +
>> +#define HSI2C_RX_FIFO_EMPTY (1u << 24)
>> +#define HSI2C_FIFO_EMPTY (HSI2C_RX_FIFO_EMPTY | \
>> + HSI2C_TX_FIFO_EMPTY)
>> +
>> +/* I2C_CONF Register bits */
>> +#define HSI2C_AUTO_MODE (1u << 31)
>> +#define HSI2C_10BIT_ADDR_MODE (1u << 30)
>> +#define HSI2C_HS_MODE (1u << 29)
>> +
>> +/* I2C_AUTO_CONF Register bits */
>> +#define HSI2C_READ_WRITE (1u << 16)
>> +#define HSI2C_STOP_AFTER_TRANS (1u << 17)
>> +#define HSI2C_MASTER_RUN (1u << 31)
>> +
>> +/* I2C_TIMEOUT Register bits */
>> +#define HSI2C_TIMEOUT_EN (1u << 31)
>> +
>> +/* I2C_TRANS_STATUS register bits */
>> +#define HSI2C_MASTER_BUSY (1u << 17)
>> +#define HSI2C_SLAVE_BUSY (1u << 16)
>> +#define HSI2C_NO_DEV (1u << 3)
>> +#define HSI2C_NO_DEV_ACK (1u << 2)
>> +#define HSI2C_TRANS_ABORT (1u << 1)
>> +#define HSI2C_TRANS_DONE (1u << 0)
>> +
>> +/* I2C_ADDR register bits */
>> +#define HSI2C_SLV_ADDR_SLV(x) ((x & 0x3ff) << 0)
>> +#define HSI2C_SLV_ADDR_MAS(x) ((x & 0x3ff) << 10)
>> +#define HSI2C_MASTER_ID(x) ((x & 0xff) << 24)
>> +
>> +/* Controller operating frequency, timing values for operation
>> + * are calculated against this frequency
>> + */
>> +#define HSI2C_HS_TX_CLOCK 1000000
>> +#define HSI2C_FS_TX_CLOCK 1000000
>> +#define HSI2C_HIGH_SPD 1
>> +#define HSI2C_FAST_SPD 0
>> +
>> +#define EXYNOS5_I2C_TIMEOUT (msecs_to_jiffies(1000))
>> +
>> +/* timeout for pm runtime autosuspend */
>> +#define EXYNOS5_I2C_PM_TIMEOUT 1000 /* ms */
>> +
>> +struct exynos5_i2c {
>> + struct i2c_adapter adap;
>> + unsigned int suspended:1;
>> +
>> + struct i2c_msg *msg;
>> + struct completion msg_complete;
>> + unsigned int msg_ptr;
>> +
>> + unsigned int irq;
>> +
>> + void __iomem *regs;
>> + struct clk *clk;
>> + struct device *dev;
>> +
>> + /* GPIO lines for SDA/SCL*/
>> + int gpios[2];
>> +
>> + /* Controller operating frequency */
>> + unsigned int clock;
>> +
>> + /* HSI2C Controller can operate in
>> + * 1. High speed upto 3.4Mbps
>> + * 2. Fast speed upto 1Mbps
>> + */
>> + int speed_mode;
>> +};
>> +
>> +static const struct of_device_id exynos5_i2c_match[] = {
>> + { .compatible = "samsung,exynos5-hsi2c" },
>> + {},
>> +};
>> +MODULE_DEVICE_TABLE(of, exynos5_i2c_match);
>> +
>> +static inline void exynos5_i2c_stop(struct exynos5_i2c *i2c)
>> +{
>> + writel(0, i2c->regs + HSI2C_INT_ENABLE);
>> +
>> + complete(&i2c->msg_complete);
>> +}
>> +
>> +static void exynos5_i2c_en_timeout(struct exynos5_i2c *i2c)
>> +{
>> + u32 i2c_timeout = readl(i2c->regs + HSI2C_TIMEOUT);
>> +
>> + /* Clear to enable Timeout */
>> + i2c_timeout &= ~HSI2C_TIMEOUT_EN;
>> + writel(i2c_timeout, i2c->regs + HSI2C_TIMEOUT);
>> +}
>> +
>> +static int exynos5_i2c_set_timing(struct exynos5_i2c *i2c)
>> +{
>> + u32 i2c_timing_s1;
>> + u32 i2c_timing_s2;
>> + u32 i2c_timing_s3;
>> + u32 i2c_timing_sla;
>> + unsigned int op_clk = i2c->clock;
>> + unsigned int clkin = clk_get_rate(i2c->clk);
>> + unsigned int n_clkdiv;
>> + unsigned int t_start_su, t_start_hd;
>> + unsigned int t_stop_su;
>> + unsigned int t_data_su, t_data_hd;
>> + unsigned int t_scl_l, t_scl_h;
>> + unsigned int t_sr_release;
>> + unsigned int t_ftl_cycle;
>> + unsigned int i = 0, utemp0 = 0, utemp1 = 0, utemp2 = 0;
>
>
> Can you think of a better name for utemp0 and utemp2? Is utemp2 a clock divisor?
Nope, utemp2 is not a clock divisor. "i" in the next loop is.
There is no real logic to name them. except for the formula described below.
Any suggestions please?
>
>>
>> +
>> + /* FPCLK / FI2C =
>> + * (CLK_DIV + 1) * (TSCLK_L + TSCLK_H + 2) + 8 + 2 * FLT_CYCLE
>> + * uTemp0 = (CLK_DIV + 1) * (TSCLK_L + TSCLK_H + 2)
>> + * uTemp1 = (TSCLK_L + TSCLK_H + 2)
>> + * uTemp2 = TSCLK_L + TSCLK_H
>> + */
>> + t_ftl_cycle = (readl(i2c->regs + HSI2C_CONF) >> 16) & 0x7;
>> + utemp0 = (clkin / op_clk) - 8 - 2 * t_ftl_cycle;
>> +
>> + /* CLK_DIV max is 256 */
>> + for (i = 0; i < 256; i++) {
>> + utemp1 = utemp0 / (i + 1);
>> + /* SCLK_L/H max is 256 / 2 */
>> + if (utemp1 < 128) {
>> + utemp2 = utemp1 - 2;
>> + break;
>> + }
>
>
> I suppose this loop can't exit until i is at least utemp / 128, so
> perhaps could start the loop at that value? This code seems to be on
> the noirq resume path, so should be fast if possible.
For me this works for i = 0 itself so never really took any time.
But, yes this can happen.

i will split the function
>
> What happens if i gets to 256? Is that an error, since in that case
> utemp2 is not set?
Right utemp2 <=0 is an error.
I'm not sure keeping the reset values of the registers intact in such
case would be a good idea,
Should i just return in probe.
>
> Also could consider moving this loop into a function.
Sure

>
>>
>> + }
>>
>> +
>> + n_clkdiv = i;
>> + t_scl_l = utemp2 / 2;
>> + t_scl_h = utemp2 / 2;
>> + t_start_su = t_scl_l;
>> + t_start_hd = t_scl_l;
>> + t_stop_su = t_scl_l;
>> + t_data_su = t_scl_l / 2;
>> + t_data_hd = t_scl_l / 2;
>> + t_sr_release = utemp2;
>> +
>> + i2c_timing_s1 = t_start_su << 24 | t_start_hd << 16 | t_stop_su << 8;
>> + i2c_timing_s2 = t_data_su << 24 | t_scl_l << 8 | t_scl_h << 0;
>> + i2c_timing_s3 = n_clkdiv << 16 | t_sr_release << 0;
>> + i2c_timing_sla = t_data_hd << 0;
>> +
>> + dev_dbg(i2c->dev, "tSTART_SU: %X, tSTART_HD: %X, tSTOP_SU: %X\n",
>> + t_start_su, t_start_hd, t_stop_su);
>> + dev_dbg(i2c->dev, "tDATA_SU: %X, tSCL_L: %X, tSCL_H: %X\n",
>> + t_data_su, t_scl_l, t_scl_h);
>> + dev_dbg(i2c->dev, "nClkDiv: %X, tSR_RELEASE: %X\n",
>> + n_clkdiv, t_sr_release);
>> + dev_dbg(i2c->dev, "tDATA_HD: %X\n", t_data_hd);
>> +
>> + if (i2c->speed_mode == HSI2C_HIGH_SPD) {
>> + writel(i2c_timing_s1, i2c->regs + HSI2C_TIMING_HS1);
>> + writel(i2c_timing_s2, i2c->regs + HSI2C_TIMING_HS2);
>> + writel(i2c_timing_s3, i2c->regs + HSI2C_TIMING_HS3);
>> + } else {
>> + writel(i2c_timing_s1, i2c->regs + HSI2C_TIMING_FS1);
>> + writel(i2c_timing_s2, i2c->regs + HSI2C_TIMING_FS2);
>> + writel(i2c_timing_s3, i2c->regs + HSI2C_TIMING_FS3);
>> + }
>> + writel(i2c_timing_sla, i2c->regs + HSI2C_TIMING_SLA);
>> +
>> + return 0;
>> +}
>> +
>> +static void exynos5_i2c_init(struct exynos5_i2c *i2c)
>> +{
>> + u32 i2c_conf = readl(i2c->regs + HSI2C_CONF);
>> +
>> + writel((HSI2C_FUNC_MODE_I2C | HSI2C_MASTER),
>> + i2c->regs + HSI2C_CTL);
>> + writel(HSI2C_TRAILING_COUNT, i2c->regs + HSI2C_TRAILIG_CTL);
>> +
>> + exynos5_i2c_set_timing(i2c);
>> +
>> + if (i2c->speed_mode == HSI2C_HIGH_SPD)
>> + i2c_conf |= HSI2C_HS_MODE;
>> +
>> + writel(i2c_conf | HSI2C_AUTO_MODE, i2c->regs + HSI2C_CONF);
>> +}
>> +
>> +static void exynos5_i2c_reset(struct exynos5_i2c *i2c)
>> +{
>> + u32 i2c_ctl;
>> +
>> + /* Set and clear the bit for reset */
>> + i2c_ctl = readl(i2c->regs + HSI2C_CTL);
>> + i2c_ctl |= HSI2C_SW_RST;
>> + writel(i2c_ctl, i2c->regs + HSI2C_CTL);
>> +
>> + i2c_ctl = readl(i2c->regs + HSI2C_CTL);
>> + i2c_ctl &= ~HSI2C_SW_RST;
>> + writel(i2c_ctl, i2c->regs + HSI2C_CTL);
>> +
>> + /* Initialize the configure registers */
>> + exynos5_i2c_init(i2c);
>> +}
>> +
>> +static void exynos5_i2c_master_run(struct exynos5_i2c *i2c)
>> +{
>> + /* Start data transfer in Master mode */
>> + u32 i2c_auto_conf = readl(i2c->regs + HSI2C_AUTO_CONF);
>> + i2c_auto_conf |= HSI2C_MASTER_RUN;
>> + writel(i2c_auto_conf, i2c->regs + HSI2C_AUTO_CONF);
>> +}
>> +
>> +/**
>> + * exynos5_i2c_irq: top level IRQ servicing routine
>> +*/
>> +static irqreturn_t exynos5_i2c_irq(int irqno, void *dev_id)
>> +{
>> + struct exynos5_i2c *i2c = dev_id;
>> + unsigned char byte;
>> +
>
>
> Can other sorts of irqs happen? Errors?
TX_ALMOSTEMPTY, RX_ALMOSTFULL, TX_UNDERRUN, TX_OVERRUN,,
RX_UNDERRUN, RX_OVERRUN, TRAILING, I2C_INT
are the possible interrupts.
>
>>
>> + if (i2c->msg->flags & I2C_M_RD) {
>> + while (!(readl(i2c->regs + HSI2C_FIFO_STATUS) &
>> + HSI2C_RX_FIFO_EMPTY)) {
>> + byte = (unsigned char)readl(i2c->regs + HSI2C_RX_DATA);
>> + i2c->msg->buf[i2c->msg_ptr++] = byte;
>> + }
>> + } else {
>> + byte = i2c->msg->buf[i2c->msg_ptr++];
>> + writel(byte, i2c->regs + HSI2C_TX_DATA);
>> +
>
>
> Extra blank line. Here you only write one byte - is there a tx FIFO
> also, so we can avoid doing one interrupt per transmit byte?
Sure, will implement in next version.
>
>>
>> + }
>> +
>> + if (i2c->msg_ptr >= i2c->msg->len)
>> + exynos5_i2c_stop(i2c);
>> +
>> + /* Set these bits to clear them */
>> + writel(readl(i2c->regs + HSI2C_INT_STATUS),
>> + i2c->regs + HSI2C_INT_STATUS);
>> +
>> + return IRQ_HANDLED;
>
>
> Are there any other interrupt types that can happen, like errors for example?
TX_ALMOSTEMPTY, RX_ALMOSTFULL, TX_UNDERRUN, TX_OVERRUN,,
RX_UNDERRUN, RX_OVERRUN, TRAILING, I2C_INT
are the possible interrupts.
No error cases
>
>>
>> +}
>> +
>> +static void exynos5_i2c_message_start(struct exynos5_i2c *i2c, int stop)
>
>
> Function comment would be useful - what is stop for?
Sure
>
>>
>> +{
>> + u32 i2c_ctl = readl(i2c->regs + HSI2C_CTL);
>> + u32 int_en = HSI2C_INT_I2C_EN;
>> + u32 i2c_auto_conf;
>> + u32 fifo_ctl;
>> +
>> + exynos5_i2c_en_timeout(i2c);
>> +
>> + fifo_ctl = HSI2C_RXFIFO_EN | HSI2C_TXFIFO_EN |
>> + HSI2C_TXFIFO_TRIGGER_LEVEL | HSI2C_RXFIFO_TRIGGER_LEVEL;
>> + writel(fifo_ctl, i2c->regs + HSI2C_FIFO_CTL);
>> +
>
>
> You could
>
> i2c_ctl &= ~(HSI2C_TXCHON | HSI2C_RXCHON)
>
> here to simply code below.
Thanks for the tip
>
>>
>> + if (i2c->msg->flags & I2C_M_RD) {
>> + i2c_ctl &= ~HSI2C_TXCHON;
>> + i2c_ctl |= HSI2C_RXCHON;
>> +
>> + i2c_auto_conf |= HSI2C_READ_WRITE;
>> +
>> + int_en |= (HSI2C_INT_RX_ALMOSTFULL_EN |
>> + HSI2C_INT_TRAILING_EN);
>> + } else {
>> + i2c_ctl &= ~HSI2C_RXCHON;
>> + i2c_ctl |= HSI2C_TXCHON;
>> +
>> + int_en |= HSI2C_INT_TX_ALMOSTEMPTY_EN;
>> + }
>> +
>> + if (stop == 1)
>> + i2c_auto_conf |= HSI2C_STOP_AFTER_TRANS;
>> +
>> + writel(HSI2C_SLV_ADDR_MAS(i2c->msg->addr), i2c->regs + HSI2C_ADDR);
>> +
>> + writel(i2c_ctl, i2c->regs + HSI2C_CTL);
>> +
>> + /* In auto mode the length of xfer cannot be 0 */
>>
>> + if (i2c->msg->len <= 0)
>
>
> What is auto mode? Perhaps a little comment at the top of the file
> about the two modes? What does it mean when msg->len < 0?
Will define.
Sorry, i don't think i2c core will ever give msg->len as 0 (unles
msg_send or msg_recv passes).
>
>>
>> + i2c_auto_conf |= 0x1;
>> + else
>> + i2c_auto_conf |= i2c->msg->len;
>> +
>> + writel(i2c_auto_conf, i2c->regs + HSI2C_AUTO_CONF);
>> +
>> + exynos5_i2c_master_run(i2c);
>> +
>> + writel(int_en, i2c->regs + HSI2C_INT_ENABLE);
>> +}
>> +
>> +static int exynos5_i2c_xfer_msg(struct exynos5_i2c *i2c,
>> + struct i2c_msg *msgs, int stop)
>> +{
>> + unsigned long timeout;
>> + u32 trans_status;
>> + u32 fifo_stat;
>> + int ret = -EAGAIN, val;
>> +
>> + i2c->msg = msgs;
>> + i2c->msg_ptr = 0;
>> +
>> + exynos5_i2c_message_start(i2c, stop);
>> +
>> + val = wait_for_completion_interruptible_timeout
>> + (&i2c->msg_complete, EXYNOS5_I2C_TIMEOUT);
>> + if (val >= 0)
>> + timeout = val;
>> +
>> + if (msgs->flags & I2C_M_RD) {
>> + if (timeout == 0) {
>> + exynos5_i2c_reset(i2c);
>> + dev_warn(i2c->dev, "rx timeout\n");
>> + return ret;
>> + }
>> +
>> + ret = 0;
>> + } else {
>> + if (timeout == 0) {
>> + exynos5_i2c_reset(i2c);
>> + dev_warn(i2c->dev, "tx timeout\n");
>> + return ret;
>> + }
>
>
> Could perhaps make the timeout check common (put above the if (msgs->flags)).
Sure
>
>>
>> +
>> + timeout = jiffies + timeout;
>> +
>> + while (time_before(jiffies, timeout)) {
>> + fifo_stat = readl(i2c->regs + HSI2C_FIFO_STATUS);
>> + trans_status = readl(i2c->regs + HSI2C_TRANS_STATUS);
>> + if ((trans_status & HSI2C_NO_DEV) ||
>> + (trans_status & HSI2C_NO_DEV_ACK &&
>> + !(i2c->msg->flags & I2C_M_IGNORE_NAK))) {
>> + exynos5_i2c_reset(i2c);
>
>
> I think these continuation lines should be indented a little more.
Sure
>
>>
>> + return -ENXIO;
>> + }
>> + if ((fifo_stat == HSI2C_FIFO_EMPTY) &&
>> + ((trans_status == 0) ||
>> + ((stop == 0) &&
>> + (trans_status == HSI2C_MASTER_BUSY)))) {
>> + ret = 0;
>> + break;
>> + }
>> + }
>>
>> + if (ret == -EAGAIN) {
>> + exynos5_i2c_reset(i2c);
>> + dev_warn(i2c->dev, "xfer timeout\n");
>> + return ret;
>> + }
>> + }
>> +
>> + return ret;
>> +}
>> +
>> +static int exynos5_i2c_xfer(struct i2c_adapter *adap,
>> + struct i2c_msg *msgs, int num)
>> +{
>> + struct exynos5_i2c *i2c = (struct exynos5_i2c *)adap->algo_data;
>> + int retry, i;
>> + int ret, ret_pm;
>> + int stop = 0;
>> + struct i2c_msg *msgs_ptr = msgs;
>> +
>> + if (i2c->suspended) {
>> + dev_err(i2c->dev, "HS-I2C is not initialzed.\n");
>> + return -EIO;
>> + }
>> +
>> + ret_pm = pm_runtime_get_sync(i2c->dev);
>> + if (IS_ERR_VALUE(ret_pm)) {
>> + ret = -EIO;
>> + goto out;
>> + }
>> +
>> + clk_prepare_enable(i2c->clk);
>> +
>> + for (retry = 0; retry < adap->retries; retry++) {
>> + for (i = 0; i < num; i++) {
>> + if (i == num - 1)
>> + stop = 1;
>
>
> Perhaps:
>
> stop = (i == num - 1);
>
> so you can avoid the other assignments to stop
Thanks for the tip
>
>>
>> + ret = exynos5_i2c_xfer_msg(i2c, msgs_ptr, stop);
>> + msgs_ptr++;
>> +
>> + if (ret == -EAGAIN) {
>> + msgs_ptr = msgs;
>> + stop = 0;
>> + break;
>> + } else if (ret == -ENXIO)
>> + goto out;
>
>
> {} around else part also I think
I thought, single line doesn't require a brace.
>
>>
>> + }
>> + if (i == num) {
>> + ret = num;
>> + goto out;
>> + }
>> +
>> + dev_dbg(i2c->dev, "retrying transfer (%d)\n", retry);
>> +
>> + udelay(100);
>> + }
>> +
>> + ret = -EREMOTEIO;
>
>
> Perhaps a dev_warn() here?
Sure
>
>>
>> + out:
>> + clk_disable_unprepare(i2c->clk);
>> + pm_runtime_mark_last_busy(i2c->dev);
>> + pm_runtime_put_autosuspend(i2c->dev);
>> + return ret;
>> +}
>> +
>> +static u32 exynos5_i2c_func(struct i2c_adapter *adap)
>> +{
>> + return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
>> +}
>> +
>> +static const struct i2c_algorithm exynos5_i2c_algorithm = {
>> + .master_xfer = exynos5_i2c_xfer,
>> + .functionality = exynos5_i2c_func,
>> +};
>> +
>> +/**
>> + * Parse a list of GPIOs from a node property and request each one
>> + *
>> + * @param i2c i2c driver data
>> + * @return 0 on success, -EINVAL on error, in which case no GPIOs requested
>> +*/
>> +static int exynos5_i2c_parse_dt_gpio(struct exynos5_i2c *i2c)
>> +{
>> + int idx, gpio, ret;
>> +
>> + for (idx = 0; idx < 2; idx++) {
>> + gpio = of_get_gpio(i2c->dev->of_node, idx);
>> + if (!gpio_is_valid(gpio)) {
>> + dev_err(i2c->dev, "invalid gpio[%d]: %d\n", idx, gpio);
>> + return -EINVAL;
>> + }
>> + i2c->gpios[idx] = gpio;
>> +
>> + ret = devm_gpio_request(i2c->dev, gpio, "i2c-bus");
>> + if (ret) {
>> + dev_err(i2c->dev, "gpio [%d] request failed\n", gpio);
>> + return -EINVAL;
>> + }
>> + }
>> + return 0;
>> +}
>> +
>> +#define HSI2C_REG(regname) {.name = #regname, .offset = regname}
>> +static struct debugfs_reg32 exynos5_hsi2c_regs[] = {
>> + HSI2C_REG(HSI2C_CTL), HSI2C_REG(HSI2C_FIFO_CTL),
>> + HSI2C_REG(HSI2C_TRAILIG_CTL), HSI2C_REG(HSI2C_CLK_CTL),
>> + HSI2C_REG(HSI2C_CLK_SLOT), HSI2C_REG(HSI2C_INT_ENABLE),
>> + HSI2C_REG(HSI2C_INT_STATUS), HSI2C_REG(HSI2C_ERR_STATUS),
>> + HSI2C_REG(HSI2C_FIFO_STATUS), HSI2C_REG(HSI2C_TX_DATA),
>> + HSI2C_REG(HSI2C_RX_DATA), HSI2C_REG(HSI2C_CONF),
>> + HSI2C_REG(HSI2C_AUTO_CONF), HSI2C_REG(HSI2C_TIMEOUT),
>> + HSI2C_REG(HSI2C_MANUAL_CMD), HSI2C_REG(HSI2C_TRANS_STATUS),
>> + HSI2C_REG(HSI2C_TIMING_HS1), HSI2C_REG(HSI2C_TIMING_HS2),
>> + HSI2C_REG(HSI2C_TIMING_HS3), HSI2C_REG(HSI2C_TIMING_FS1),
>> + HSI2C_REG(HSI2C_TIMING_FS2), HSI2C_REG(HSI2C_TIMING_FS3),
>> + HSI2C_REG(HSI2C_TIMING_SLA), HSI2C_REG(HSI2C_ADDR),
>> +};
>> +
>> +static struct debugfs_regset32 exynos5_hsi2c_regset = {
>> + .regs = exynos5_hsi2c_regs,
>> + .nregs = ARRAY_SIZE(exynos5_hsi2c_regs),
>> +};
>> +
>> +static struct dentry *exynos5_hsi2c_reg_debugfs;
>> +
>> +static int exynos5_i2c_probe(struct platform_device *pdev)
>> +{
>> + struct device_node *np = pdev->dev.of_node;
>> + struct exynos5_i2c *i2c;
>> + int ret;
>> +
>> + if (!np) {
>> + dev_err(&pdev->dev, "no device node\n");
>> + return -ENOENT;
>> + }
>> +
>> + i2c = devm_kzalloc(&pdev->dev, sizeof(struct exynos5_i2c), GFP_KERNEL);
>> + if (!i2c) {
>> + dev_err(&pdev->dev, "no memory for state\n");
>> + return -ENOMEM;
>> + }
>> +
>> + /* Mode of operation High/Fast Speed mode */
>> + if (of_get_property(np, "samsung,hs-mode", NULL)) {
>> + i2c->speed_mode = 1;
>> + if (of_property_read_u32(np, "samsung,hs-clock", &i2c->clock))
>> + i2c->clock = HSI2C_HS_TX_CLOCK;
>> + } else {
>> + i2c->speed_mode = 0;
>> + if (of_property_read_u32(np, "samsung,fs-clock", &i2c->clock))
>> + i2c->clock = HSI2C_FS_TX_CLOCK;
>> + }
>> +
>> + strlcpy(i2c->adap.name, "exynos5-i2c", sizeof(i2c->adap.name));
>> + i2c->adap.owner = THIS_MODULE;
>> + i2c->adap.algo = &exynos5_i2c_algorithm;
>> + i2c->adap.retries = 2;
>> + i2c->adap.class = I2C_CLASS_HWMON | I2C_CLASS_SPD;
>> +
>> + i2c->dev = &pdev->dev;
>> + i2c->clk = devm_clk_get(&pdev->dev, "hsi2c");
>> + if (IS_ERR(i2c->clk)) {
>> + dev_err(&pdev->dev, "cannot get clock\n");
>> + return -ENOENT;
>> + }
>> +
>> + clk_prepare_enable(i2c->clk);
>> +
>> + i2c->regs = of_iomap(np, 0);
>> + if (!i2c->regs) {
>> + dev_err(&pdev->dev, "cannot map HS-I2C IO\n");
>> + ret = -EADDRNOTAVAIL;
>> + goto err_clk;
>> + }
>> +
>> + i2c->adap.algo_data = i2c;
>> + i2c->adap.dev.parent = &pdev->dev;
>> +
>> + /* parse device tree and inititalise the gpio */
>> + if (exynos5_i2c_parse_dt_gpio(i2c))
>> + return -EINVAL;
>> +
>> + init_completion(&i2c->msg_complete);
>> +
>> + i2c->irq = ret = irq_of_parse_and_map(np, 0);
>> + if (ret <= 0) {
>> + dev_err(&pdev->dev, "cannot find HS-I2C IRQ\n");
>> + goto err_iomap;
>> + }
>> +
>> + ret = devm_request_irq(&pdev->dev, i2c->irq, exynos5_i2c_irq,
>> + 0, dev_name(&pdev->dev), i2c);
>> +
>> + if (ret != 0) {
>> + dev_err(&pdev->dev, "cannot request HS-I2C IRQ %d\n", i2c->irq);
>> + goto err_iomap;
>> + }
>> +
>> + /*
>> + * TODO: Use private lock to avoid race conditions as
>> + * mentioned in pm_runtime.txt
>> + */
>> + pm_runtime_enable(i2c->dev);
>> + pm_runtime_set_autosuspend_delay(i2c->dev, EXYNOS5_I2C_PM_TIMEOUT);
>> + pm_runtime_use_autosuspend(i2c->dev);
>> +
>> + ret = pm_runtime_get_sync(i2c->dev);
>> + if (IS_ERR_VALUE(ret))
>> + goto err_iomap;
>> +
>> + exynos5_i2c_init(i2c);
>> + i2c->adap.nr = -1;
>> + i2c->adap.dev.of_node = np;
>> +
>> + ret = i2c_add_numbered_adapter(&i2c->adap);
>> + if (ret < 0) {
>> + dev_err(&pdev->dev, "failed to add bus to i2c core\n");
>> + goto err_pm;
>> + }
>> +
>> + of_i2c_register_devices(&i2c->adap);
>> + platform_set_drvdata(pdev, i2c);
>> +
>> + exynos5_hsi2c_reg_debugfs = debugfs_create_regset32("exynos5-hsi2c",
>> + S_IFREG | S_IRUGO,
>> + NULL, &exynos5_hsi2c_regset);
>> + clk_disable_unprepare(i2c->clk);
>> + pm_runtime_mark_last_busy(i2c->dev);
>> + pm_runtime_put_autosuspend(i2c->dev);
>> +
>> + return 0;
>> +
>> + err_pm:
>> + pm_runtime_put(i2c->dev);
>> + pm_runtime_disable(&pdev->dev);
>> + err_iomap:
>> + iounmap(i2c->regs);
>> + err_clk:
>> + clk_disable_unprepare(i2c->clk);
>> + return ret;
>> +}
>> +
>> +static int exynos5_i2c_remove(struct platform_device *pdev)
>> +{
>> + struct exynos5_i2c *i2c = platform_get_drvdata(pdev);
>> + int ret;
>> +
>> + ret = pm_runtime_get_sync(&pdev->dev);
>> + if (IS_ERR_VALUE(ret))
>> + return ret;
>> +
>> + clk_disable_unprepare(i2c->clk);
>> + pm_runtime_put(&pdev->dev);
>> + pm_runtime_disable(&pdev->dev);
>> +
>> + i2c_del_adapter(&i2c->adap);
>> +
>> + iounmap(i2c->regs);
>> +
>> + return 0;
>> +}
>> +
>> +#ifdef CONFIG_PM
>> +static int exynos5_i2c_suspend_noirq(struct device *dev)
>
>
> Have you selected the noirq methods for a reason? I am just interested
> in how you decided to use suspend_noirq() instead of suspend().
I've taken the reference from s3c24xx driver.
My understanding is suspend late and resume faster.
Kindly, help.
>
>>
>> +{
>> + struct platform_device *pdev = to_platform_device(dev);
>> + struct exynos5_i2c *i2c = platform_get_drvdata(pdev);
>> +
>> + i2c->suspended = 1;
>> +
>> + return 0;
>> +}
>> +
>> +static int exynos5_i2c_resume_noirq(struct device *dev)
>> +{
>> + struct platform_device *pdev = to_platform_device(dev);
>> + struct exynos5_i2c *i2c = platform_get_drvdata(pdev);
>> +
>> + clk_prepare_enable(i2c->clk);
>> + exynos5_i2c_init(i2c);
>> + clk_disable_unprepare(i2c->clk);
>> + i2c->suspended = 0;
>> +
>> + return 0;
>> +}
>> +
>> +static const struct dev_pm_ops exynos5_i2c_dev_pm_ops = {
>> + .suspend_noirq = exynos5_i2c_suspend_noirq,
>> + .resume_noirq = exynos5_i2c_resume_noirq,
>> +};
>> +
>> +#define EXYNOS5_DEV_PM_OPS (&exynos5_i2c_dev_pm_ops)
>> +#else
>> +#define EXYNOS5_DEV_PM_OPS NULL
>> +#endif
>> +
>> +static struct platform_driver exynos5_i2c_driver = {
>> + .probe = exynos5_i2c_probe,
>> + .remove = exynos5_i2c_remove,
>> + .driver = {
>> + .owner = THIS_MODULE,
>> + .name = "exynos5-hsi2c",
>> + .pm = EXYNOS5_DEV_PM_OPS,
>> + .of_match_table = of_match_ptr(exynos5_i2c_match),
>> + },
>> +};
>> +
>> +static int __init i2c_adap_exynos5_init(void)
>> +{
>> + return platform_driver_register(&exynos5_i2c_driver);
>> +}
>> +subsys_initcall(i2c_adap_exynos5_init);
>> +
>> +static void __exit i2c_adap_exynos5_exit(void)
>> +{
>> + platform_driver_unregister(&exynos5_i2c_driver);
>> +}
>> +module_exit(i2c_adap_exynos5_exit);
>> +
>> +MODULE_DESCRIPTION("Exynos5 HS-I2C Bus driver");
>> +MODULE_AUTHOR("Naveen Krishna Chatradhi, <ch.naveen-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>");
>> +MODULE_AUTHOR("Taekgyun Ko, <taeggyun.ko-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>");
>> +MODULE_LICENSE("GPL");
>> --
>> 1.7.9.5
>>
>
> Regards,
> Simon
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--
Shine bright,
(: Nav :)