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SubjectRE: [EXT] Re: [PATCH 1/2] i2c: imx: I2C Driver doesn't consider I2C_IPGCLK_SEL RCW bit when using ls1046a SoC
Date


> -----Original Message-----
> From: Sascha Hauer <s.hauer@pengutronix.de>
> Sent: 2019年5月6日 15:48
> To: Chuanhua Han <chuanhua.han@nxp.com>
> Cc: shawnguo@kernel.org; Leo Li <leoyang.li@nxp.com>; robh+dt@kernel.org;
> mark.rutland@arm.com; linux-kernel@vger.kernel.org;
> linux-i2c@vger.kernel.org; linux-arm-kernel@lists.infradead.org;
> devicetree@vger.kernel.org; festevam@gmail.com; dl-linux-imx
> <linux-imx@nxp.com>; wsa+renesas@sang-engineering.com;
> u.kleine-koenig@pengutronix.de; eha@deif.com; linux@rempel-privat.de;
> l.stach@pengutronix.de; peda@axentia.se; Sumit Batra
> <sumit.batra@nxp.com>
> Subject: [EXT] Re: [PATCH 1/2] i2c: imx: I2C Driver doesn't consider
> I2C_IPGCLK_SEL RCW bit when using ls1046a SoC
>
> Caution: EXT Email
>
> Hi,
>
> In case we end up with the handling of this issue in the i2c driver, here are the
> things to consider for v2.
>
> On Tue, Apr 30, 2019 at 12:47:18PM +0800, Chuanhua Han wrote:
> > The current kernel driver does not consider I2C_IPGCLK_SEL (424 bit of
> > RCW) in deciding i2c_clk_rate in function i2c_imx_set_clk() { 0
> > Platform clock/4, 1 Platform clock/2}.
> >
> > When using ls1046a SoC, this populates incorrect value in IBFD
> > register if I2C_IPGCLK_SEL = 0, which generates half of the desired Clock.
> >
> > Therefore, if ls1046a SoC is used, we need to set the i2c clock
> > according to the corresponding RCW.
> >
> > Signed-off-by: Sumit Batra <sumit.batra@nxp.com>
> > Signed-off-by: Chuanhua Han <chuanhua.han@nxp.com>
> > ---
> > drivers/i2c/busses/i2c-imx.c | 64
> > ++++++++++++++++++++++++++++++++++++
> > 1 file changed, 64 insertions(+)
> >
> > diff --git a/drivers/i2c/busses/i2c-imx.c
> > b/drivers/i2c/busses/i2c-imx.c index 422f1a445b55..7186cf3c7d24 100644
> > --- a/drivers/i2c/busses/i2c-imx.c
> > +++ b/drivers/i2c/busses/i2c-imx.c
> > @@ -45,6 +45,8 @@
> > #include <linux/pm_runtime.h>
> > #include <linux/sched.h>
> > #include <linux/slab.h>
> > +#include <linux/fsl/guts.h>
> > +#include <linux/sys_soc.h>
> >
> > /* This will be the driver name the kernel reports */ #define
> > DRIVER_NAME "imx-i2c"
> > @@ -109,6 +111,21 @@
> >
> > #define I2C_PM_TIMEOUT 10 /* ms */
> >
> > +/* 14-1 Since array index starts from 0 */ #define
> > +RCW_I2C_IPGCLK_WORD (14 - 1)
> > +/*
> > + * Set mask for RCW 424th bit, reading from DCFG_CCSR RCW Status
> > +Registers
> > + * Since this register in RM depicted as big endian,
> > + * so consider 31st bit as LSB for creating the mask.
> > + */
> > +#define RCW_I2C_IPGCLK_MASK 0x800000
> > +int i2c_ipgclk_sel = 1;
>
> should be static.
>
> > +
> > +static const struct soc_device_attribute ls1046a_soc[] = {
> > + {.family = "QorIQ LS1046A"},
> > + { /* sentinel */ }
> > +};
> > +
> > /*
> > * sorted list of clock divider, register value pairs
> > * taken from table 26-5, p.26-9, Freescale i.MX @@ -304,6 +321,11 @@
> > static const struct platform_device_id imx_i2c_devtype[] = { };
> > MODULE_DEVICE_TABLE(platform, imx_i2c_devtype);
> >
> > +static const struct of_device_id guts_device_ids[] = {
> > + { .compatible = "fsl,qoriq-device-config", },
> > + {}
> > +};
> > +
> > static const struct of_device_id i2c_imx_dt_ids[] = {
> > { .compatible = "fsl,imx1-i2c", .data = &imx1_i2c_hwdata, },
> > { .compatible = "fsl,imx21-i2c", .data = &imx21_i2c_hwdata, },
> > @@ -533,6 +555,9 @@ static void i2c_imx_set_clk(struct imx_i2c_struct
> *i2c_imx,
> > unsigned int div;
> > int i;
> >
> > + if (!i2c_ipgclk_sel)
> > + i2c_clk_rate = i2c_clk_rate / 2;
>
> It would be nice to have the variable inverted. You wouldn't have to initialize a
> global variable with something else but 0 then.
>
> > +
> > /* Divider value calculation */
> > if (i2c_imx->cur_clk == i2c_clk_rate)
> > return;
> > @@ -551,6 +576,10 @@ static void i2c_imx_set_clk(struct imx_i2c_struct
> *i2c_imx,
> > /* Store divider value */
> > i2c_imx->ifdr = i2c_clk_div[i].val;
> >
> > + pr_alert("[%s] CLK Rate=%u Bitrate =%u Div =%u Value =%d\n",
> > + __func__, i2c_clk_rate, i2c_imx->bitrate,
> > + div, i2c_clk_div[i].val);
>
> Please drop your debugging aids, for sure they shouldn't be pr_alert.
>
> > +
> > /*
> > * There dummy delay is calculated.
> > * It should be about one I2C clock period long.
> > @@ -1116,6 +1145,9 @@ static int i2c_imx_probe(struct platform_device
> *pdev)
> > int irq, ret;
> > dma_addr_t phy_addr;
> > u32 mul_value;
> > + struct device_node *guts_node;
> > + static struct ccsr_guts __iomem *guts_regs;
> > + u32 rcw_reg;
> >
> > dev_dbg(&pdev->dev, "<%s>\n", __func__);
> >
> > @@ -1135,6 +1167,38 @@ static int i2c_imx_probe(struct platform_device
> *pdev)
> > if (!i2c_imx)
> > return -ENOMEM;
> >
> > + if (soc_device_match(ls1046a_soc)) {
> > + /*
> > + * Make device node for GUTS/DCFG (global utilities block)
> > + * to read RCW.
> > + */
> > + guts_node = of_find_matching_node(NULL,
> guts_device_ids);
> > + if (!guts_node) {
> > + dev_err(&pdev->dev, "Could not find GUTS
> node\n");
> > + return -ENODEV;
> > + }
> > + /*
> > + * Memory (IO) MAP the DCFG registers(for RCW) to
> > + * be used in kernel virtual address space.
> > + */
> > + guts_regs = of_iomap(guts_node, 0);
> > + of_node_put(guts_node);
> > + if (!guts_regs) {
> > + dev_err(&pdev->dev, "IOREMAP of GUTS node
> failed\n");
> > + return -ENOMEM;
> > + }
> > + /* Read rcw bit 424 (starting from 0) */
> > + rcw_reg =
> ioread32be(&guts_regs->rcwsr[RCW_I2C_IPGCLK_WORD]);
> > + pr_alert("RCW REG[%d]=0x%x\n", RCW_I2C_IPGCLK_WORD,
> rcw_reg);
> > + if (rcw_reg & RCW_I2C_IPGCLK_MASK) {
> > + pr_alert("Div by 2 Case Detected in RCW\n");
> > + i2c_ipgclk_sel = 1;
> > + } else {
> > + pr_alert("Div by 4 Case Detected in RCW\n");
> > + i2c_ipgclk_sel = 0;
> > + }
> > + }
>
> This is done once per i2c controller, but it sets a variable valid for all controllers.
> Either execute this code once outside of device specific context or use a
> variable in driver data and not a global one.
Do you mean the global variable "i2c_ipgclk_sel"?
>
> Sascha
>
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