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Date: Sun, 27 Apr 2014 22:23:13 +0200
From: Heiko Stübner <heiko@...ech.de>
To: Max Schwarz <max.schwarz@...ine.de>
Cc: Wolfram Sang <wsa@...-dreams.de>,
Grant Likely <grant.likely@...aro.org>,
Rob Herring <robh+dt@...nel.org>, linux-i2c@...r.kernel.org,
linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH] i2c: add driver for Rockchip RK3xxx SoC I2C adapter
Hi Max,
first of all, thanks for working on this :-)
I saw some general things inlined below, but I guess Wolfram is the better
person to check the i2c-specifics.
Am Sonntag, 27. April 2014, 21:38:49 schrieb Max Schwarz:
> Driver for the native I2C adapter found in Rockchip RK3xxx SoCs.
[...]
> diff --git a/Documentation/devicetree/bindings/i2c/i2c-rk3x.txt
> b/Documentation/devicetree/bindings/i2c/i2c-rk3x.txt new file mode 100644
> index 0000000..6778985
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/i2c/i2c-rk3x.txt
> @@ -0,0 +1,33 @@
> +* Rockchip RK3xxx I2C controller
> +
> +This driver interfaces with the native I2C controller present in Rockchip
> +RK3xxx SoCs.
> +
> +Required properties :
> +
> + - reg : Offset and length of the register set for the device
> + - compatible : should be "rockchip,rk3x-i2c"
> + - interrupts : interrupt number
> + - clocks : parent clock
> + - grf : the phandle of the syscon node for the general register file (GRF)
> + - bus-idx : index of the bus in the GRF
both the grf as well as the bus-idx are rockchip specific, so they should be
prefixed (rockchip,grf, etc) and from my personal taste I would hope we could
invest in an "n" and "e", to make it a full bus-index ;-)
> +
> +Optional properties :
> +
> + - frequency : SCL frequency to use (in Hz). If omitted, 100kHz is used.
the convention seems to be "clock-frequency" for the desired bus speed
(checked i2c-sirf, i2c-exynos, i2c-at91and i2c-qup).
> +
> +Example:
> +
> +i2c0: i2c@...2d000 {
> + compatible = "rockchip,rk3x-i2c";
> + reg = <0x2002d000 0x1000>;
> + interrupts = <GIC_SPI 40 IRQ_TYPE_LEVEL_HIGH>;
> + #address-cells = <1>;
> + #size-cells = <0>;
> +
> + grf = <&grf>;
> + bus-idx = <0>;
> +
> + clock-names = "i2c";
> + clocks = <&cru PCLK_I2C0>;
> +};
> diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
> index c94db1c..f973632 100644
> --- a/drivers/i2c/busses/Kconfig
> +++ b/drivers/i2c/busses/Kconfig
> @@ -663,6 +663,16 @@ config I2C_PXA_SLAVE
> is necessary for systems where the PXA may be a target on the
> I2C bus.
>
> +config I2C_RK3X
> + tristate "Rockchip RK3xxx I2C adapter"
> + depends on OF
> + help
> + Say Y here to include support for the I2C adapter in Rockchip RK3xxx
> + SoCs.
> +
> + This driver can also be built as a module. If so, the module will
> + be called i2c-rk3x.
> +
> config I2C_QUP
> tristate "Qualcomm QUP based I2C controller"
> depends on ARCH_QCOM
> diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
> index 18d18ff..39b6851 100644
> --- a/drivers/i2c/busses/Makefile
> +++ b/drivers/i2c/busses/Makefile
> @@ -65,6 +65,7 @@ obj-$(CONFIG_I2C_PNX) += i2c-pnx.o
> obj-$(CONFIG_I2C_PUV3) += i2c-puv3.o
> obj-$(CONFIG_I2C_PXA) += i2c-pxa.o
> obj-$(CONFIG_I2C_PXA_PCI) += i2c-pxa-pci.o
> +obj-$(CONFIG_I2C_RK3X) += i2c-rk3x.o
> obj-$(CONFIG_I2C_QUP) += i2c-qup.o
> obj-$(CONFIG_I2C_RIIC) += i2c-riic.o
> obj-$(CONFIG_I2C_S3C2410) += i2c-s3c2410.o
> diff --git a/drivers/i2c/busses/i2c-rk3x.c b/drivers/i2c/busses/i2c-rk3x.c
> new file mode 100644
> index 0000000..00491b0
> --- /dev/null
> +++ b/drivers/i2c/busses/i2c-rk3x.c
> @@ -0,0 +1,728 @@
> +/*
> + * Driver for I2C unit in Rockchip RK3188 SoC
RK3188 -> RK3xxx?
> + *
> + * Max Schwarz <max.schwarz@...ine.de>
> + * based on the patches by Rockchip Inc.
> + *
> + * 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/i2c.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/io.h>
> +#include <linux/of_address.h>
> +#include <linux/of_irq.h>
> +#include <linux/spinlock.h>
> +#include <linux/clk.h>
> +#include <linux/wait.h>
> +#include <linux/mfd/syscon.h>
> +#include <linux/regmap.h>
> +
> +
> +/* Register Map */
> +#define REG_CON 0x00 /* control register */
> +#define REG_CLKDIV 0x04 /* clock divisor register */
> +#define REG_MRXADDR 0x08 /* slave address for REGISTER_TX */
> +#define REG_MRXRADDR 0x0c /* slave register address for REGISTER_TX */
> +#define REG_MTXCNT 0x10 /* number of bytes to be transmitted */
> +#define REG_MRXCNT 0x14 /* number of bytes to be received */
> +#define REG_IEN 0x18 /* interrupt enable */
> +#define REG_IPD 0x1c /* interrupt pending */
> +#define REG_FCNT 0x20 /* finished count */
> +
> +/* Data buffer offsets */
> +#define TXBUFFER_BASE 0x100
> +#define RXBUFFER_BASE 0x200
> +
> +/* REG_CON bits */
> +#define REG_CON_EN (1 << 0)
> +enum {
> + REG_CON_MOD_TX = 0, /* transmit data */
> + REG_CON_MOD_REGISTER_TX, /* select register and restart */
> + REG_CON_MOD_RX, /* receive data */
> + REG_CON_MOD_REGISTER_RX, /* broken: transmits read addr AND writes
> + * register addr */
> +};
> +#define REG_CON_MOD(mod) ((mod) << 1)
> +#define REG_CON_MOD_MASK (3 << 1)
> +#define REG_CON_START (1 << 3)
> +#define REG_CON_STOP (1 << 4)
> +#define REG_CON_LASTACK (1 << 5) /* 1: do not send ACK after last receive
> */ +#define REG_CON_ACTACK (1 << 6) /* 1: stop if NACK is received */ +
> +/* REG_MRXADDR bits */
> +#define REG_MRXADDR_LOW (1 << 24) /* bits [7:0] of MRX[R]ADDR are valid
> */ +#define REG_MRXADDR_MID (1 << 25) /* bits [15:8] of MRX[R]ADDR are
> valid */ +#define REG_MRXADDR_HIGH (1 << 26) /* bits [23:16] of MRX[R]ADDR
> are valid */ +
> +/* REG_IEN/REG_IPD bits */
> +#define REG_INT_BTF (1 << 0) /* a byte was transmitted */
> +#define REG_INT_BRF (1 << 1) /* a byte was received */
> +#define REG_INT_MBTF (1 << 2) /* master data transmit finished */
> +#define REG_INT_MBRF (1 << 3) /* master data receive finished */
> +#define REG_INT_START (1 << 4) /* START condition generated */
> +#define REG_INT_STOP (1 << 5) /* STOP condition generated */
> +#define REG_INT_NAKRCV (1 << 6) /* NACK received */
> +#define REG_INT_ALL 0x7f
> +
> +/* Registers in the GRF (General Register File) */
> +#define GRF_SOC_CON1 4
> +
> +/* Constants */
> +#define WAIT_TIMEOUT 200 /* ms */
> +
> +enum rk3x_i2c_state {
> + STATE_IDLE,
> + STATE_START,
> + STATE_READ,
> + STATE_WRITE,
> + STATE_STOP
> +};
> +
> +struct rk3x_i2c {
> + struct i2c_adapter adap;
> + struct device *dev;
> +
> + /* Hardware resources */
> + void __iomem *regs;
> + struct regmap *grf;
> + unsigned int bus_idx;
> + struct clk *clk;
> + int irq;
> +
> + /* Settings */
> + unsigned int scl_frequency;
> +
> + /* Synchronization & notification */
> + spinlock_t lock;
> + wait_queue_head_t wait;
> + bool busy;
> +
> + /* Current message */
> + struct i2c_msg *msg;
> + u8 addr;
> + unsigned int mode;
> +
> + /* I2C state machine */
> + enum rk3x_i2c_state state;
> + unsigned int processed; /* sent/received bytes */
> + int error;
> +};
> +
> +static inline void i2c_writel(struct rk3x_i2c *i2c, u32 value,
> + unsigned int offset)
> +{
> + writel(value, i2c->regs + offset);
> +}
> +
> +static inline u32 i2c_readl(struct rk3x_i2c *i2c, unsigned int offset)
> +{
> + return readl(i2c->regs + offset);
> +}
I'm not sure what the policy here is, but is this indirection really necessary
when it's only doing a normal readl/writel?
Heiko
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