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linux-next/drivers/clk/clk-plldig.c
Colin Ian King 73cb3106e8 clk: ls1028a: fix a dereference of pointer 'parent' before a null check
Currently the pointer 'parent' is being dereferenced before it is
being null checked. Fix this by performing the null check before
it is dereferenced.

Addresses-Coverity: ("Dereference before null check")
Fixes: d37010a3c1 ("clk: ls1028a: Add clock driver for Display output interface")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Link: https://lkml.kernel.org/r/20200203223736.99645-1-colin.king@canonical.com
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
2020-02-03 23:03:49 -08:00

289 lines
7.0 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* Copyright 2019 NXP
*
* Clock driver for LS1028A Display output interfaces(LCD, DPHY).
*/
#include <linux/clk-provider.h>
#include <linux/device.h>
#include <linux/module.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/iopoll.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/bitfield.h>
/* PLLDIG register offsets and bit masks */
#define PLLDIG_REG_PLLSR 0x24
#define PLLDIG_LOCK_MASK BIT(2)
#define PLLDIG_REG_PLLDV 0x28
#define PLLDIG_MFD_MASK GENMASK(7, 0)
#define PLLDIG_RFDPHI1_MASK GENMASK(30, 25)
#define PLLDIG_REG_PLLFM 0x2c
#define PLLDIG_SSCGBYP_ENABLE BIT(30)
#define PLLDIG_REG_PLLFD 0x30
#define PLLDIG_FDEN BIT(30)
#define PLLDIG_FRAC_MASK GENMASK(15, 0)
#define PLLDIG_REG_PLLCAL1 0x38
#define PLLDIG_REG_PLLCAL2 0x3c
/* Range of the VCO frequencies, in Hz */
#define PLLDIG_MIN_VCO_FREQ 650000000
#define PLLDIG_MAX_VCO_FREQ 1300000000
/* Range of the output frequencies, in Hz */
#define PHI1_MIN_FREQ 27000000UL
#define PHI1_MAX_FREQ 600000000UL
/* Maximum value of the reduced frequency divider */
#define MAX_RFDPHI1 63UL
/* Best value of multiplication factor divider */
#define PLLDIG_DEFAULT_MFD 44
/*
* Denominator part of the fractional part of the
* loop multiplication factor.
*/
#define MFDEN 20480
static const struct clk_parent_data parent_data[] = {
{ .index = 0 },
};
struct clk_plldig {
struct clk_hw hw;
void __iomem *regs;
unsigned int vco_freq;
};
#define to_clk_plldig(_hw) container_of(_hw, struct clk_plldig, hw)
static int plldig_enable(struct clk_hw *hw)
{
struct clk_plldig *data = to_clk_plldig(hw);
u32 val;
val = readl(data->regs + PLLDIG_REG_PLLFM);
/*
* Use Bypass mode with PLL off by default, the frequency overshoot
* detector output was disable. SSCG Bypass mode should be enable.
*/
val |= PLLDIG_SSCGBYP_ENABLE;
writel(val, data->regs + PLLDIG_REG_PLLFM);
return 0;
}
static void plldig_disable(struct clk_hw *hw)
{
struct clk_plldig *data = to_clk_plldig(hw);
u32 val;
val = readl(data->regs + PLLDIG_REG_PLLFM);
val &= ~PLLDIG_SSCGBYP_ENABLE;
val |= FIELD_PREP(PLLDIG_SSCGBYP_ENABLE, 0x0);
writel(val, data->regs + PLLDIG_REG_PLLFM);
}
static int plldig_is_enabled(struct clk_hw *hw)
{
struct clk_plldig *data = to_clk_plldig(hw);
return readl(data->regs + PLLDIG_REG_PLLFM) &
PLLDIG_SSCGBYP_ENABLE;
}
static unsigned long plldig_recalc_rate(struct clk_hw *hw,
unsigned long parent_rate)
{
struct clk_plldig *data = to_clk_plldig(hw);
u32 val, rfdphi1;
val = readl(data->regs + PLLDIG_REG_PLLDV);
/* Check if PLL is bypassed */
if (val & PLLDIG_SSCGBYP_ENABLE)
return parent_rate;
rfdphi1 = FIELD_GET(PLLDIG_RFDPHI1_MASK, val);
/*
* If RFDPHI1 has a value of 1 the VCO frequency is also divided by
* one.
*/
if (!rfdphi1)
rfdphi1 = 1;
return DIV_ROUND_UP(data->vco_freq, rfdphi1);
}
static unsigned long plldig_calc_target_div(unsigned long vco_freq,
unsigned long target_rate)
{
unsigned long div;
div = DIV_ROUND_CLOSEST(vco_freq, target_rate);
div = clamp(div, 1UL, MAX_RFDPHI1);
return div;
}
static int plldig_determine_rate(struct clk_hw *hw,
struct clk_rate_request *req)
{
struct clk_plldig *data = to_clk_plldig(hw);
unsigned int div;
req->rate = clamp(req->rate, PHI1_MIN_FREQ, PHI1_MAX_FREQ);
div = plldig_calc_target_div(data->vco_freq, req->rate);
req->rate = DIV_ROUND_UP(data->vco_freq, div);
return 0;
}
static int plldig_set_rate(struct clk_hw *hw, unsigned long rate,
unsigned long parent_rate)
{
struct clk_plldig *data = to_clk_plldig(hw);
unsigned int val, cond;
unsigned int rfdphi1;
rate = clamp(rate, PHI1_MIN_FREQ, PHI1_MAX_FREQ);
rfdphi1 = plldig_calc_target_div(data->vco_freq, rate);
/* update the divider value */
val = readl(data->regs + PLLDIG_REG_PLLDV);
val &= ~PLLDIG_RFDPHI1_MASK;
val |= FIELD_PREP(PLLDIG_RFDPHI1_MASK, rfdphi1);
writel(val, data->regs + PLLDIG_REG_PLLDV);
/* waiting for old lock state to clear */
udelay(200);
/* Wait until PLL is locked or timeout */
return readl_poll_timeout_atomic(data->regs + PLLDIG_REG_PLLSR, cond,
cond & PLLDIG_LOCK_MASK, 0,
USEC_PER_MSEC);
}
static const struct clk_ops plldig_clk_ops = {
.enable = plldig_enable,
.disable = plldig_disable,
.is_enabled = plldig_is_enabled,
.recalc_rate = plldig_recalc_rate,
.determine_rate = plldig_determine_rate,
.set_rate = plldig_set_rate,
};
static int plldig_init(struct clk_hw *hw)
{
struct clk_plldig *data = to_clk_plldig(hw);
struct clk_hw *parent = clk_hw_get_parent(hw);
unsigned long parent_rate;
unsigned long val;
unsigned long long lltmp;
unsigned int mfd, fracdiv = 0;
if (!parent)
return -EINVAL;
parent_rate = clk_hw_get_rate(parent);
if (data->vco_freq) {
mfd = data->vco_freq / parent_rate;
lltmp = data->vco_freq % parent_rate;
lltmp *= MFDEN;
do_div(lltmp, parent_rate);
fracdiv = lltmp;
} else {
mfd = PLLDIG_DEFAULT_MFD;
data->vco_freq = parent_rate * mfd;
}
val = FIELD_PREP(PLLDIG_MFD_MASK, mfd);
writel(val, data->regs + PLLDIG_REG_PLLDV);
/* Enable fractional divider */
if (fracdiv) {
val = FIELD_PREP(PLLDIG_FRAC_MASK, fracdiv);
val |= PLLDIG_FDEN;
writel(val, data->regs + PLLDIG_REG_PLLFD);
}
return 0;
}
static int plldig_clk_probe(struct platform_device *pdev)
{
struct clk_plldig *data;
struct device *dev = &pdev->dev;
int ret;
data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
if (!data)
return -ENOMEM;
data->regs = devm_platform_ioremap_resource(pdev, 0);
if (IS_ERR(data->regs))
return PTR_ERR(data->regs);
data->hw.init = CLK_HW_INIT_PARENTS_DATA("dpclk",
parent_data,
&plldig_clk_ops,
0);
ret = devm_clk_hw_register(dev, &data->hw);
if (ret) {
dev_err(dev, "failed to register %s clock\n",
dev->of_node->name);
return ret;
}
ret = devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get,
&data->hw);
if (ret) {
dev_err(dev, "unable to add clk provider\n");
return ret;
}
/*
* The frequency of the VCO cannot be changed during runtime.
* Therefore, let the user specify a desired frequency.
*/
if (!of_property_read_u32(dev->of_node, "fsl,vco-hz",
&data->vco_freq)) {
if (data->vco_freq < PLLDIG_MIN_VCO_FREQ ||
data->vco_freq > PLLDIG_MAX_VCO_FREQ)
return -EINVAL;
}
return plldig_init(&data->hw);
}
static const struct of_device_id plldig_clk_id[] = {
{ .compatible = "fsl,ls1028a-plldig" },
{ }
};
MODULE_DEVICE_TABLE(of, plldig_clk_id);
static struct platform_driver plldig_clk_driver = {
.driver = {
.name = "plldig-clock",
.of_match_table = plldig_clk_id,
},
.probe = plldig_clk_probe,
};
module_platform_driver(plldig_clk_driver);
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Wen He <wen.he_1@nxp.com>");
MODULE_DESCRIPTION("LS1028A Display output interface pixel clock driver");