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Date: Wed, 5 Nov 2014 13:37:21 +0200
From: Roger Quadros <rogerq@...com>
To: <wg@...ndegger.com>, <mkl@...gutronix.de>,
Tomi Valkeinen <tomi.valkeinen@...com>
CC: <wsa@...-dreams.de>, <tony@...mide.com>, <tglx@...utronix.de>,
<mugunthanvnm@...com>, <george.cherian@...com>, <balbi@...com>,
<nsekhar@...com>, <nm@...com>,
<sergei.shtylyov@...entembedded.com>, <linux-omap@...r.kernel.org>,
<linux-can@...r.kernel.org>, <netdev@...r.kernel.org>
Subject: Re: [PATCH v3 4/8] net: can: c_can: Add syscon/regmap RAMINIT mechanism
On 11/04/2014 12:20 PM, Roger Quadros wrote:
> Some TI SoCs like DRA7 have a RAMINIT register specification
> different from the other AMxx SoCs and as expected by the
> existing driver.
>
> To add more insanity, this register is shared with other
> IPs like DSS, PCIe and PWM.
>
> Provides a more generic mechanism to specify the RAMINIT
> register location and START/DONE bit position and use the
> syscon/regmap framework to access the register.
>
> Signed-off-by: Roger Quadros <rogerq@...com>
> ---
> .../devicetree/bindings/net/can/c_can.txt | 3 +
> drivers/net/can/c_can/c_can.h | 9 ++-
> drivers/net/can/c_can/c_can_platform.c | 93 +++++++++++++---------
> 3 files changed, 65 insertions(+), 40 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/net/can/c_can.txt b/Documentation/devicetree/bindings/net/can/c_can.txt
> index 8f1ae81..917ac0e 100644
> --- a/Documentation/devicetree/bindings/net/can/c_can.txt
> +++ b/Documentation/devicetree/bindings/net/can/c_can.txt
> @@ -12,6 +12,9 @@ Required properties:
> Optional properties:
> - ti,hwmods : Must be "d_can<n>" or "c_can<n>", n being the
> instance number
> +- syscon-raminit : Handle to system control region that contains the
> + RAMINIT register and register offset to the RAMINIT
> + register.
>
> Note: "ti,hwmods" field is used to fetch the base address and irq
> resources from TI, omap hwmod data base during device registration.
> diff --git a/drivers/net/can/c_can/c_can.h b/drivers/net/can/c_can/c_can.h
> index c3b2108..b5067bd 100644
> --- a/drivers/net/can/c_can/c_can.h
> +++ b/drivers/net/can/c_can/c_can.h
> @@ -178,6 +178,12 @@ struct c_can_driver_data {
> bool raminit_pulse; /* If set, sets and clears START bit (pulse) */
> };
>
> +/* Out of band RAMINIT register access via syscon regmap */
> +struct c_can_raminit {
> + struct regmap *syscon; /* for raminit ctrl. reg. access */
> + unsigned int reg; /* register index within syscon */
> +};
> +
> /* c_can private data structure */
> struct c_can_priv {
> struct can_priv can; /* must be the first member */
> @@ -195,8 +201,7 @@ struct c_can_priv {
> const u16 *regs;
> void *priv; /* for board-specific data */
> enum c_can_dev_id type;
> - u32 __iomem *raminit_ctrlreg;
> - int instance;
> + struct c_can_raminit raminit_sys; /* RAMINIT via syscon regmap */
> void (*raminit) (const struct c_can_priv *priv, bool enable);
> u32 comm_rcv_high;
> u32 rxmasked;
> diff --git a/drivers/net/can/c_can/c_can_platform.c b/drivers/net/can/c_can/c_can_platform.c
> index 11946e8..d0ce439 100644
> --- a/drivers/net/can/c_can/c_can_platform.c
> +++ b/drivers/net/can/c_can/c_can_platform.c
> @@ -32,14 +32,13 @@
> #include <linux/clk.h>
> #include <linux/of.h>
> #include <linux/of_device.h>
> +#include <linux/mfd/syscon.h>
> +#include <linux/regmap.h>
>
> #include <linux/can/dev.h>
>
> #include "c_can.h"
>
> -#define CAN_RAMINIT_START_MASK(i) (0x001 << (i))
> -#define CAN_RAMINIT_DONE_MASK(i) (0x100 << (i))
> -#define CAN_RAMINIT_ALL_MASK(i) (0x101 << (i))
> #define DCAN_RAM_INIT_BIT (1 << 3)
> static DEFINE_SPINLOCK(raminit_lock);
> /*
> @@ -72,47 +71,61 @@ static void c_can_plat_write_reg_aligned_to_32bit(const struct c_can_priv *priv,
> writew(val, priv->base + 2 * priv->regs[index]);
> }
>
> -static void c_can_hw_raminit_wait_ti(const struct c_can_priv *priv, u32 mask,
> - u32 val)
> +static void c_can_hw_raminit_wait_syscon(const struct c_can_priv *priv,
> + u32 mask, u32 val)
> {
> int timeout = 0;
> + const struct c_can_raminit *raminit = &priv->raminit_sys;
> + u32 ctrl;
> +
> /* We look only at the bits of our instance. */
> val &= mask;
> - while ((readl(priv->raminit_ctrlreg) & mask) != val) {
> + do {
> udelay(1);
> timeout++;
>
> + regmap_read(raminit->syscon, raminit->reg, &ctrl);
> if (timeout == 1000) {
> dev_err(&priv->dev->dev, "%s: time out\n", __func__);
> break;
> }
> - }
> + } while ((ctrl & mask) != val);
> }
>
> -static void c_can_hw_raminit_ti(const struct c_can_priv *priv, bool enable)
> +static void c_can_hw_raminit_syscon(const struct c_can_priv *priv, bool enable)
> {
> - u32 mask = CAN_RAMINIT_ALL_MASK(priv->instance);
> + u32 mask;
> u32 ctrl;
> + const struct c_can_raminit *raminit = &priv->raminit_sys;
> + u8 start_bit, done_bit;
> +
> + start_bit = priv->drvdata->raminit_start_bit;
> + done_bit = priv->drvdata->raminit_done_bit;
>
> spin_lock(&raminit_lock);
>
> - ctrl = readl(priv->raminit_ctrlreg);
> + mask = 1 << start_bit | 1 << done_bit;
> + regmap_read(raminit->syscon, raminit->reg, &ctrl);
> +
> /* We clear the done and start bit first. The start bit is
> * looking at the 0 -> transition, but is not self clearing;
> * And we clear the init done bit as well.
> + * NOTE: DONE must be written with 1 to clear it.
> */
> - ctrl &= ~CAN_RAMINIT_START_MASK(priv->instance);
> - ctrl |= CAN_RAMINIT_DONE_MASK(priv->instance);
> - writel(ctrl, priv->raminit_ctrlreg);
> - ctrl &= ~CAN_RAMINIT_DONE_MASK(priv->instance);
> - c_can_hw_raminit_wait_ti(priv, mask, ctrl);
> + ctrl &= ~(1 << start_bit);
> + ctrl |= 1 << done_bit;
> + regmap_write(raminit->syscon, raminit->reg, ctrl);
Thanks to Tomi for pointing out.
I need to use regmap_update_bits() instead of regmap_write() for atomic modification,
as this register needs to be shared between multiple drivers in case of DRA7 SoC.
cheers,
-roger
> +
> + ctrl &= ~(1 << done_bit);
> + c_can_hw_raminit_wait_syscon(priv, mask, ctrl);
>
> if (enable) {
> /* Set start bit and wait for the done bit. */
> - ctrl |= CAN_RAMINIT_START_MASK(priv->instance);
> - writel(ctrl, priv->raminit_ctrlreg);
> - ctrl |= CAN_RAMINIT_DONE_MASK(priv->instance);
> - c_can_hw_raminit_wait_ti(priv, mask, ctrl);
> + ctrl |= 1 << start_bit;
> + regmap_write(raminit->syscon, raminit->reg, ctrl);
> +
> + ctrl |= 1 << done_bit;
> + c_can_hw_raminit_wait_syscon(priv, mask, ctrl);
> }
> spin_unlock(&raminit_lock);
> }
> @@ -206,10 +219,11 @@ static int c_can_plat_probe(struct platform_device *pdev)
> struct net_device *dev;
> struct c_can_priv *priv;
> const struct of_device_id *match;
> - struct resource *mem, *res;
> + struct resource *mem;
> int irq;
> struct clk *clk;
> const struct c_can_driver_data *drvdata;
> + struct device_node *np = pdev->dev.of_node;
>
> match = of_match_device(c_can_of_table, &pdev->dev);
> if (match) {
> @@ -279,27 +293,30 @@ static int c_can_plat_probe(struct platform_device *pdev)
> priv->read_reg32 = d_can_plat_read_reg32;
> priv->write_reg32 = d_can_plat_write_reg32;
>
> - if (pdev->dev.of_node)
> - priv->instance = of_alias_get_id(pdev->dev.of_node, "d_can");
> - else
> - priv->instance = pdev->id;
> -
> - res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
> - /* Not all D_CAN modules have a separate register for the D_CAN
> - * RAM initialization. Use default RAM init bit in D_CAN module
> - * if not specified in DT.
> + /* Check if we need custom RAMINIT via syscon. Mostly for TI
> + * platforms. Only supported with DT boot.
> */
> - if (!res) {
> + if (np && of_property_read_bool(np, "syscon-raminit")) {
> + ret = -EINVAL;
> + priv->raminit_sys.syscon = syscon_regmap_lookup_by_phandle(np,
> + "syscon-raminit");
> + if (IS_ERR(priv->raminit_sys.syscon)) {
> + dev_err(&pdev->dev,
> + "couldn't get syscon regmap for RAMINIT reg.\n");
> + goto exit_free_device;
> + }
> +
> + if (of_property_read_u32_index(np, "syscon-raminit", 1,
> + &priv->raminit_sys.reg)) {
> + dev_err(&pdev->dev,
> + "couldn't get the RAMINIT reg. offset!\n");
> + goto exit_free_device;
> + }
> +
> + priv->raminit = c_can_hw_raminit_syscon;
> + } else {
> priv->raminit = c_can_hw_raminit;
> - break;
> }
> -
> - priv->raminit_ctrlreg = devm_ioremap(&pdev->dev, res->start,
> - resource_size(res));
> - if (!priv->raminit_ctrlreg || priv->instance < 0)
> - dev_info(&pdev->dev, "control memory is not used for raminit\n");
> - else
> - priv->raminit = c_can_hw_raminit_ti;
> break;
> default:
> ret = -EINVAL;
>
--
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